Not a huge fan of this last episode. Peter damn well knows he absorbs powers and that he wants to avoid blowing up, so why did he actively seek out Ted? I knew it was bound to happen, but I had hoped for an accidental confrontation, not "who's Ted? Let's find him!"
The Sylar/mom bit was cool, but I think it would have been more effective if it had played out over 2 episodes, personally.
I have 2 theories on the conclusion of this season, and both revolve around the bomb (ie Peter) going off and the future we saw in episode 20 becoming a reality. So far, every time Hiro has attempted to alter the past, he has failed to do so. I think future Hiro is having a similar issue. He thought that saving claire would prevent Sylar from healing, but it was apparent in episode 20 that Claire had been saved and that future Hiro had changed nothing. So, how did Sylar survive? Well, two theories, like I said.
1. Peter absorbs illusionist's powers and, in an attempt to shift the blame for the explosion (a successful shift, according to episode 20), becomes Sylar. Hiro stabs him, but is unsuccessful, as Peter can heal.
2. Sylar is the bomb and is stabbed by Hiro. He does not have Claire's power. Rather, Linderman heals Sylar to insure his "Ozymandias" like plot becomes reality.
Perhaps a combo of these is how it will all end, where Linderman has the heroes chasing Sylar when really it's Peter that blows up. I don't know, but regardless, I think next season will feature a new cast living in the post New York bombing world.