Another three perakim!

Hadran Alach Mavoi!
Hadran Alach Osin Pasin!
Hadran Alach BeChol MeArvin!
(1st, 2nd, 3rd perek bavli eruvin)

There is a famous analysis showing that Santa Claus is no longer with us, having burned up while trying to deliver presents. I've often speculated on Eliyahu HaNavi being able to visit all the sedarim on pesach night.

Informative is a gemara in Eruvin, daf 43a:
"These seven rulings were said on the morning of Shabbat before Rav Chisda in the city of Sura and were repeated in the afternoon of Shabbat before Rava in Pumpedisa. Who said them? Was it not Eliyahu {who could travel this distance in so short a time, which was more than the techum, and was flying and thus travelling over 10 tefachim from the ground}? Therefore derive that there are no techumin over 10 tefachim! No! Perhaps it was Yosef the demon who said it."

Thus, at least one problem - how Eliyahu could visit all of these Jewish houses if it means leaving the techum - is solved. There is also a basis for Eliyahu travelling really really fast.
:) :) :)
The continuation of the gemara is aso really interesting...check it out.

Disclaimer: Eliyahu doesn't really visit the Jewish homes on pesach night. I think this belief arose because we pour the Kos Shel Eliyahu, "Elijah's cup," immediately before getting up and opening the door to say "Shefoch Chamosecha," "Pour Out Your Wrath." It is called the Kos of Eliyahu because there is a dispute whether to pour and drink four or five cups of wine, a dispute which Eliyahu will come and resolve in Messianic times. In the meantime, out of doubt, we pour but do not drink. People see the pouring of "Eliyahu's Cup," saw we open the door, and made up that we are opening the door for Eliyahu who is coming to drink his cup.

Update: The gemara is actually proof by omission that Eliyahu does not visit every seder. After all, the gemara suggests that it was Yosef the demon who spread the message about the shev shma`ta, the seven rulings. The gemara lets this pass unchallenged as a refutation to the absolute proof that there is no techum over 10 tefachim. The gemara did not then say that Eliyahu visits homes on Passover night, which is a yom tov, and thus should be subject to techum. Thus, it seems that the amoraim/savoraim did not subscribe to the view that Eliyahu actually visits.