Today is my 34th birthday. Not so much different from my 33rd, or 32nd or 31st for that matter.
I think once you turn 30, birthdays stop becoming quite such a big deal for you and start becoming a big deal for the people around you. Friends and family always asking "So how does it feel?", or "Feel any different?", or other silly questions like that. And then instead of you heading out with friends to go out and party and get drunk, they're the ones dragging your tired ass out after work to see how drunk they can get you. If they're anything like my friends back home, they've probably also got pools going on how long it takes to get to the first spew of the night. Or having the bartenter add a few extra shots to your drinks without telling you.
For me, it'll be just another day, although perhaps I'll treat myself with a trip out to Best Buy or the bookstore and buy me something.