As of jan 2012
100M max for website
20 meg max size per attachment, should be fine for mp3's of up to 20min audio
see current file and site size limit
* can't rename files
* originally it appeared to have no hierarchical folders, only one flat level file directory. Actually, you can have folders, it's just tricky to figure out. You create subpages, and then under subpages, you can create a page of type "file cabinet" and move files there.
* however, the "folders" that appear under a file cabinet are not real folders in a file system sense, files are stored as a flat file system even if you create subfolders from the file cabinet.
* easy for malicious collaborators to intentionally delete all the files. It seems to keep all the deleted files around for 4 weeks before deleting permanently, so one should be able to recover accidental deletes.
Basically, it looks like googlesites was designed intentionally to prevent anyone from using it as a large data file repository, only for collaboration of html pages and small projects.