Uh, spoiler stuff for BSG fans.
All of you should be BSG fans. To that end, I will gladly point you to a high quality direct download of the first three hours of the show. PM me. All of you. I mean it.
My theory is that Starbuck went through a wormhole in the eye of that storm and came out in the eye of a very similar storm in the eye of Jupiter. She went to Earth and she didn't exactly have a jump-capable ship, so she had to be close.
Also, at the end of S3E20, Kara's in a model of Viper that we've never seen before. I've watched that scene about a dozen times now. It's something between the Cylon-War-era Galactica Vipers and the modern one that Apollo pilots. It has more curvy parts than the old ones.
Ronald Moore has said that he hasn't decided who the last Cylon is. They are kind of hedging their bets with Starbuck and with Rosalin but both of THEM seem to be related to the prophecy in the scriptures, which kind of implies a human origin. Leoben said Adama is a Cylon and if you look back, everything a Leoben has said has eventually come to pass, except the ongoing issue of trying to make a "family" with Starbuck. So there's a credible notion there as well.
There's also something from Season 1: The scrolls of Pythia said that men would receive aid from a "Lower Demon" which at the time was thought to refer to Sharon. Now, with all those seconds-in-command being Cylons, there's all kinds of ways to interpret that little clue.
Getting back to the new Cylons... I'm not entirely convinced of their status. Tigh fought in the first Cylon war, before they had humanoid Cylons. Anders making it to Galactica as part of any Cylon conspiracy is WAY improbable, considering how he got on board. Tyrol also has a long and established history on Galactica and, even more, has been directly told by Cavil that he ISN'T a Cylon (plus his kid would be a hybrid, and therefore all special like Hera... and no one cares about the Chief's kid). They all heard the music and ended up in the same place so I think they're making an assumption about who/what they are.
Um, anyway, I just typed several paragraphs of random and massively geeky speculation about a science fiction TV show. This is not my proudest moment.