[flipzmode]

I had this error on my phone a couple of days ago when pushing some files, but I actually went and looked (Settings > SD Card and Phone Storage > Available space at bottom of screen) and I had 90mb free. I rebooted the phone and the error went away.

I currently have 137mb free on Fresh .05. I would say that the average size app is about 1mb. You would have to have well over 100 apps installed to actually be running out of space because of it.