I believe that some variation of this limit is what is causing problems for a lot of folks.
My experience is that if I have more than 78 or 79 apps installed in my /var/mobile/Applications folder, I will get stuck on the boot screen if I attempt to use Cydia or SSH to install something in the /Applications folder. Even before I jailbroke, it seemed that once I got in that range of installed Apps, the likelihood of crashing was very high if I attempted to update via the AppStore on the phone. So far, however, I seem to be able to install higher numbers than that if I do it through iTunes (ver 7.7). As I increase above that, those installations or updates get quite slow, so for now, I've decided to stay below 79 apps in that folder. So far, so good.
Also, I think version 7.7.1 of iTunes is EVIL. I had nothing but problems until I downgraded and NONE since.
Here's a link to what I think is a great analysis of the problem, as well as the best workaround I've seen:
http://www.hackint0sh.org/forum/showthread.php?t=49782