Two articles make reference to the event. The first is in Russian and the second is in Romanian. (I have a very rough translation of the Russian article but the relevant facts are summarized above.)
May God grant him many years!
(Via an email from Carlos Antonio Palad)
An Update: Below is an English translation of the Russian article linked above thanks to Fr. Yousuf Rassam.
30 August 2010.
Metropoltian Kallistos of Dioclea and Hieromonk Gabriel (Bunge) Concelebrate All-night Vigil with Metrpolitan Hilarion of Volokolamsk in the Church of the Icon "Joy of All that Sorrow" on Bolshoy Ordinka Street.
On 27 August 2010, on the eve of the Feast of the Dormition of the most holy Theotokos, Metropolitan Hilarion of Volokolamsk celebrated the all-night vigil in the church of the Icon, "Joy of All that Sorrow" on Bolshoy Ordinka Street.
Vladyka Hilarion concelebrated with Metropolitan Kallistos of Dioclea, vicar of the Archbishop of Thyateira and Great Britain of the Constantinople Patriarchate, chairman of the British benevolent society "Friends of Mount Athos"; the clergy of the church, and also the well known Swiss theologian and Hieromonk Gabriel (Bunge), who was received into holy Orthodoxy before the all-night vigil.
In the church were praying numerous parishioners, and also pilgrims from Great Britain, the USA, Greece, and other countries - members of the delegation of the benevolent society "Friends of Mount Athos". The aim of society is to disseminate knowledge of the Holy Mountain and the monastic tradition, helping to restore the monasteries of Mount Athos, and attracting pilgrims to Mount Athos. The delegation of the society is visiting Russia with the blessing of His Holiness Kirill, Patriarch of Moscow and All Russia. During the journey, the pilgrims visited Uglich, Kostroma, Yaroslavl, Rostov, Nizhny Novgorod, Gorodets, Kalyazin, and theTrinity-Sergius Lavra and venerated the holy places of the Russian Orthodox Church.
After the service, Metropolitan Hilarion delivered this with arch-pastoral homily:
"Your Eminence, Venerable Father, dear brothers and sisters!
I heartily congratulate you on the occasion of the Dormition of the most holy Theotokos. On this day, before the grave of our moust holy Lady and Ever-Virgin Mary, we celebrate her Dormition and at the same time think about our own life and death. Man is called to live on this earth a full life, a life that is spiritual and divine. The end of such a life should not be a tragic event, but a natural transition to eternal life - not death but falling asleep (dormition).
The most holy Theotokos, by her grave, which exudes grace, peace, and love, bears witness that it is possible for the dead to pass from death to life, from sin - to grace, from human life - to life divine.
The Church believes that the Mother of God never sinned, not only in deed, but even in thought. We with you are shown to be sinful people, but for us the way to the Kingdom of Heaven is not closed. This path leads through death, which may be a falling asleep, if our life is accordant with the commandments of God, and if we pray to the Lord and His Most Pure Mother that we be granted a blameless and peaceful end, which will be for us a transition into life eternal. "
Metropoltian Hilarion of Volokolamsk , chairman of the Department of External Church Relations (of the Moscow Patriarchate, the OVTsS or DECR), addressed Metropolitan Kallistos of Dioclea in particular:
"I offer a hearty welcome the Vladyka Kallistos, who is a hierarch of the Patriarchate of Constantinople, and for more than 40 years has been teaching at Oxford University in Britain. 15 years ago I had the good fortune to learn from him: Vladyka was supervisor for my work on a dissertation about Saint Symeon the New Theologian. Today, Metropolitan Kallistos is one of the most famous theologians of Ecumenical Patriarchate. In Moscow, he arrived at the head of the pilgrimage group, which includes clergy, professors, and ordinary laymen. For ten days this group has been traveling through the cities of Russia, venerating the holy places of our land, becoming acquainted with our spiritual culture. On the day of the feast of the Dormition of the Most Holy Theotokos, Bishop Kallistos will concelebrate with His Holiness Patriarch Kyrill in the Dormition Cathedral of the Moscow Kremlin.
I welcome you not only as a hierarch and an outstanding theologian, but as my teacher and friend. It is my desire that your time in the Russian land was a blessing, and that the Lord will help you in both pastoral ministry and academic writing, and that He will preserve for many blessed years. "
In memory of the con-celebration, Metropolitan Hilarion of Volokolamsk presented to Vladyka Kallistos the gift of a miter, made in the workshops of the Moscow Patriarchate.
Vladyka Hilarion also heartily welcomed hieromonk Gabriel (Bunge), who, for more than 30 years has lived a hermetical life in the mountains of Switzerland. "You were a Catholic, but in soul you were Orthodox" - Metropolitan Hilarion said to him - "Today, before the all-night vigil, you converted to Orthodoxy, which was a natural conclusion of a long spiritual journey. "
Metropolitan Hilarion warmly congratulated Father Gabriel on his reception into holy Orthodoxy, and gave him an icon of the Heavenly Queen, "Joy of All Who Sorrow" in memory of the fact that he was united to the Orthodox Church in this church, consecrated in honor of this icon.
In his response, referring to the chairman of the DECR, Metropolitan Kallistos of Dioclea said:
"Concelebrating with you on the eve of the feast of the Dormition of the Most Holy Theotokos is, for me, a great joy and honor. For many years, I have kept fond memories of your stay in Oxford. It is particularly gratifying that over the ensuing years, we are in constant contact, and often encounter one another ... I believe that thanks to the protection of the Most Holy Theotokos, the very significant ministry that you carry in this church, and in your labors for Universal Orthodoxy, will be aided by grace from the Lord.
I am also pleased to learn that today Father Gabriel is united to Orthodoxy in this church. We highly esteem his theological works, and I hope that the cross of the Orthodox Christian, which he has taken upon himself, will not be too heavy for him. I pray that the Most Holy Theotokos will fill your hearts with joy and consolation".