Ok, so a few weeks back I discovered that everytime I rebooted my Storm I never gained any memory back and quite often started with even less. I barely had any apps, ony UberTwitter, App World, and a couple of games. I assumed the culprit was UberTwitter. I deleted it, but I still wasn't gaining any memory back after a reboot.
In the end, I said screw it and ended up re-installing 328. Nice I was now booting at about 51.9MB again. I didn't put UberTwitter back on, and everything was cool for a while. I would only lose about 0.02MB over the course of several days just from basic use of the phone.
However, yesterday I decided to browse through App World for a while, and when I closed it out, I noticed I lost about 3MB. I was like wow, this app is a hog, and decided to reboot the phone. The memory didn't come back. I rebooted again. No change. I pulled the battery. Still no change. After several battery pulls, I never got that lost 3MB back.
I decided to uninstall App World to see if that would help. Sure enough, it did. My startup memory went back up to about 51.6MB. It appears that App World caches all those app icons and screenshots in the app memory and never lets go of them. Uninstalling App World itself was the only way to flush out that memory. For 1st party software, App World sure is written poorly. Why would you use app memory to cache images when there is so much device memory available?
I realize now that App World was the problem originally. That's fine. I can always just send an app to my phone through App World's website, instead. So for anyone else who is losing memory and can't figure out why, if you have App World, that could be your problem.