What happened in 1054?

We all know that 1054 marks the beginning of the unfortunate schism between the East and the West. But, canonically speaking, what really happened that year?

Some have posited the interesting position that the schism did not begin in 1054 and that what actually happened in 1054 was inconsequential canonically (though it may have been of monumental importance culturally). This would not imply that the east is not in schism, but it would question when they went into schism.
Here's a brief rundown of what led up to the 1054 schism and some things to think about:
Following the Norman conquest of southern Italy in the early 1050's, the Normans began forcibly imposing Latin customs on the Greek churches in Calabria and Sicily, Churches which had maintained a happy coexistence with both Rome and Constantinople for centuries.
Seeing that the popes had fallen under the sway of the Normans (Pope Leo IX was even held prisoner by them on 1053), the Greek Italian churches pleaded with the Patriarch of Constantinople to assist them in maintaining their cultural and liturgical identity. Patriarch Michael I Cerularius ordered the head of the Bulgarian church to draft a letter to be sent to all of the western bishops, including the pope, in which the Latin Church was accused of "Judaizing" (a reference to the west's use of unleavened bread for the Eucharist).
Pope Leo ordered Cardinal Humbert to make a reply to the charges, and sent him, along with Frederick of Lorraine (future Pope Stephen IX) and Archbishop Peter of Amalfi, to Constantinople empowered with legatine powers to answer the charges made against the Latin Church. When they arrived, they immediately got into a heated quarrel with the Patriarch and stormed out of his palace. The Patriarch refused to recognize their authority and would not meet with them anymore.
Meanwhile, Leo IX died on April 19, 1054. The legates waited around Constantinople for several more months, until their anger drove them to their famous act: on July 16, they entered Hagia Sophia during the Divine Liturgy and placed a Bull of Excommunication upon the altar, then left for Rome. The city was in riots over the Bull, and the legates were lucky to escape with their lives. The legates were in turn anathematized by a Byzantine Synod.
Though this was undoubtedly a momentous event culturally, what canonical legitimacy did the mutual excommunications have? Did the actions of Cardinal Humbert, Peter of Amalfi and Frederick of Lorraine place the east in a formal state of schism according to the Church's canonical tradition? A few things to consider:
First, the powers of a legate expire when the pope who grants the legatine powers dies. Pope Leo IX died in April, and the legatine powers were not reconferred upon Humbert, Frederick and Peter, at least not prior to their return to Rome. Therefore, when the excommunication was declared, in July, their legatine powers had expired four months earlier. The excommunications would have to be either affirmed by the new pope or Michael Cerularius would have to be excommunicated again by a legate with legitimate powers.
Second, their bull only excommunicated Michael I, not any other person. Even if it was valid, it would have expired after Michael's death and not carried on to his successor, much less any of the other eastern bishops, much less to the orthodox as such.
Third, the anathemas against the legates named only Humbert, Peter and Frederick. Not even the pope was anathematized. Thus, the idea of two churches mutually excommunicating each other is way overblown. Cerularius was excommunicated by the legates, and the legates were anathematized by Cerularius. Thus accounts that state the two churches excommunicated one another gravely misconstrue the facts - as if a whole body of people can be excommunicated. The proper object of excommunication is an individual, not a collective.
Did the schism begin in 1054 then? Culturally, perhaps, but canonically no. If not, what prevented an immediate reconciliation? No doubt the presence of the Latin kingdoms in the Holy Land after the First Crusade (in formerly Byzantine territories) exacerbated a sense of competition and ill will, perpetuating a "cultural schism" that we can clearly see in the writings of Anna Comnena, the Byzantine princess who chronicled the First Crusade and tells us without must equivocation that the Latin Franks are filthy barbarians. A persistence of these sorts of attitudes, on both sides, made 1054 difficult to undo.

This cultural schism was definitely solidified in 1204, when the Latins took control of Constantinople and the deep seated Greek hatred for the Latins became irreversible. The point is that the schism was a gradual process with no definable date for when it started or when it was consummated. 1054 has simply served as a convenient marker along the way, though canonically, it is doubtful that anything binding or irreformable took place in that year. Some point to the Council of Lyons (1272-1274) as the point of formal schism, where the Greek Church formally pledged unity with the Roman See and then broke that pledge soon after the Council.

Pray for the reunion of the Greek and Latin Churches.