Just saw this float by. I've looked at it in the past but couldn't use it since the required image plugins weren't on my shared hosting but I now see they're builtin - so I had to try it over currently using WP Smushit.
So wow, it's great.
Only issue is the bulk optimise doesn't seem to work for me. I just get a page with the title and nothing else and I have left it for some time. The individual optimizing works wonderfully though.