Scalability is going to be a huge focus from the community this year due to recent changes at MySQL. Tweakers.net has a pretty good breakdown of the present mySQL binary with and without the fix to INNODB scalability bug.
Tweakers.net also has an interesting comparison of POSTGRES on various platforms. It's behaving nicely under high concurrency, much better then INNODB even with the patch to it's scalability bug. If Falcon ever gets released it would be nice to Bench it.
If I get some time, I might run some of my own benchmarks to see what else can be squeezed out of MySQL.