The questions "Is it authentic? When was it written? Why is it in the Talmud?" and so on, are mine.
Oh I thought you were asking these questions rhetorically and then offering the article as an answer since it does deal with these questions.
The Talmud was redacted ~500 CE. So figure around that time. Obviously, I believe that the contents of the Talmud are based on traditions that preceded it., including this passage. The author of that article also concludes that it may have been an authentic tradition.
The Mishnah says that before a conviction they make an announcement to see if anyone knows anything that can help the defendant. This passage was brought as an illustration of that.
What was the evidence used to convict this Jesus?
The Jewish system is not exactly evidence based. You don't need to bring fingerprints. You bring witnesses (Deut. 17:6, 19:15).
Is this Jesus mentioned elsewhere in the Talmud?
In 6,000 double sided pages, there's maybe three or four mentions. Maybe five. He wasn't an important topic to Babylonian Jews in 500 CE.
Is this Jesus mentioned anywhere else in Jewish writings?
Not in this manner.
How common was it to be convicted of sorcery during this time period?
I don't know about conviction. But sorcery and witchcraft are mentioned a number of times in the Talmud and other writing.
Is his disciples mentioned elsewhere in the Talmud?[/SIZE]
Not to my knowledge, but I don't claim to know the entire Talmud, its quite long. Still I think I would have heard about it. There is mention of other people using his name to perform healing though.