Welcome back to Magic after a long absence. There are quite a few new game mechanics, and more than a few major retools of the rules (no interrupts, combat damage no longer uses the stack).
Current trends are:
Standard = Pinger Naya from Pro Tour San Diego.
U/W Jace Control is also popular.
http://www.wizards.com/magic/magazine/a ... opstddecks.....JUND??!(the best deck in the t2 format by far, not even close, the deck literally has almost no bad matchups)
Extended = Dark Depths & Zoo are considered Tier 1.
Check out recent decklists from Grand Prix Oakland for recently successful Extended decks.
http://www.wizards.com/Magic/Magazine/A ... 10/welcomeAlso decklists for many things found here:
http://www.deckcheck.net/