I attended an instructional workshop on the Passover last night at St. Joseph's in Hillsborough. It was led by Gregory Glazov, Assistant Professor of Biblical Studies at Immaculate Conception Seminary's school of Theology (at Seton Hall). This was a more intensive look at the Passover Seder, and Greg made a number of important theological connections. The bread and cup of wine that Jesus blessed, for example, most likely coincide with the afikomen and third cup (the cup of redemption, also called the cup of blessing).
Also brought up was the way in which the Passover meal was not a "memorial", per se, but was a making-present of the Passover celebrated in Egypt. In the same way, Catholics believe the Eucharist at the altar is not a "memorial" or representation (what most non-Catholic Christians believe) but rather the making-present of the new Passover meal, the body and blood of the true Lamb, re-presented as though we were there receiving it when it was first instituted. Jesus inserted himself into the Passover ritual, and stopped things after that third cup. While he was in Gethsemane, he prayed that the cup might pass him by: perhaps the "cup of wrath" or perhaps the fourth cup of the passover (the cup of restoration).
It was an excellent experience, and there was good conversation as well. I plan on looking at Psalms 113-118 (the Hallel) at Bible Study during Holy Week; hopefully, I can work some of this information in.