In case you're curious (I am!), iStat Menus can show you the breakdown with its battery monitor module.

Keep in mind that the reduction in battery life might also just be that you have more intensive apps running, more things happening in the background, brighter monitor, etc. I also feel intuitively like the battery life in my MBP has dropped, but seeing the numbers, I'm pretty convinced it's a change in my usage more than the inherent battery life.