Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Consider that Lion for the most part is a bit more taxing and compare it to what you were getting in Snow Leopard. If the times are not off by a lot, consider it normal.
 
My 2010 got a hit on battery life with lion also. 6-7 (SL) to about 5 (lion) like you said.
 
I get around five hours on Lion, as well. Apple will continue to update the OS in order to fix bugs and add new/improve features. Maybe battery life will get better after an update or two.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.