I have been running into issues where I was running out of space on the Internal SD card. I had an app that was using about 400MB, so I removed that. I also moved all of my pictures and videos to the external card last week, but it still looked like something was using up a lot of space. I discovered that there is a file in \DCIM\.thumbnails on the internal card named .thumbdata3--1967290299 . This file is 285 meg on my device. If you google that filename, you will find all kinds of posts about the file growing to 1gig or more and causing performance/crashing issues on various Android devices. There are posted workarounds where it is suggested to put an empty file there with the same name. According to these posts if you just delete the file, it will be recreated the next time you boot. Just to test this, I deleted the file and did not put an empty one in it's place. I rebooted the device, and so far it has not recreated the file. I do see in the gallery the thumbnails seem to be a little out of whack. It shows a bunch of empty pictures between the real ones, but I'm not sure it wasn't like that before (might have happened when I moved my pictures to the external card). I have a feeling that the file will eventually come back, so I'll be watching for that.
I'm thinking that our customers who might be using the camera a lot may have this issue (as well as the issue where the camera app only uses the internal SD card for storage).