Well, today I was just curious what my memory levels were so I fired up the task manager and saw 68MB free. Oddly enough a few hours later it jumped back up to 91MB free. So, I am convinced that at least part of it was due to a 3rd party application that was eating memory.
I just had the OTA update pushed to me, so I installed it. When it first booted I had about 15 apps listed in the task manager....but it showed 101MB free. So I killed them all and there was no change in the memory allocated. My guess is this is the result of the "Battery life is improved." fix in the 2.01 release. It's hard to say what they did to improve this. It could have been that the OS was not properly freeing resources when an application was killed or they could have somehow improved how non-running processes use memory. I'm guessing it's the latter. That's the only way to explain how I had 15 applications showing up in the task manager after a reboot and not taking up any memory while still being responsive.
So unless my phone starts getting slow again I am going to consider it fixed.