[slparry]

Out of interest I took a peek at how much memory was in use before I did a reboot of the device and it was using half a gigabyte less after the restart, so I guess just like pc's it's probably a good idea to reboot them occasionally

[dracolnyte]

my guess is, just like a PC, it has used, unused, and free memory. the unused is not recorded under free because it is caching whatever previous app you had open. just in case you open it again, it will access the memory more quickly. but if the unused memory is needed for a memory-hogging app like a game, it will use them.
just my theory