I had a guy at work tell me that he'd read about turning AWE on for 64bit SQL. That sounded TOTALLY wrong to me, so I checked BOL, which says "AWE is not required and cannot be configured on 64-bit operating systems." I got all self-satisfied, but then I thought, I'd better check with the internetz.
Thanks to Denny Cherry (@mrdenny on Twitter) for pointing me to a reputable resource: Bob Ward's most excellent CSS SQL Server Engineers article "Fun with Locked Pages, AWE, Task Manager, and the Working Set…". This in essence says that BOL is right in one sense: the sp_configure option for AWE makes absolutely no difference for 64-bit SQL. But you can get the effect of "locking pages" (not to be confused with page locks) by using the 'lock pages in memory' privilege set. (See also Bob's accompanying article Do I have to assign the Lock Pages in Memory privilege for Local System?).
Edit: Here's a blog by Slava Oks that also addresses 64bit and AWE (thanks for the link goes to Mladen Prajdic)
Bottom line: AWE has NO effect on 64 bit systems! (And, you set "lock pages in memory" independently, if that's the behavior you're looking for.)
-Jen McCown