This seasons TV series are from me (in random order) and far from complete list:

• Prison Break (first 2 episodes aired)
• Heroes (seems to start this month)
• Lost (seems to start this month)
• Dexter, Pre-Air episode 1 is available (already seen)
• Californication, Pre Air Season 2, episode 1 and & 2 are available

and thanks to the comments I can add more:

• Supernatural (seen all seasons)
• Bones (only saw all official DVD episodes)
• BattleStar Gallactica, I should also not forget
• Smallville

Searching for other TV-series worth to watch ..