Filecloud currently has the following hard-coded exclusions to prevent the syncing of system files and folders as well as certain temporary application files.

GENERAL EXCLUSIONS

Filename beginning with ~
Filenames ending with ~
.temp folder and anything below it

DIRECTORY EXCLUSIONS

/WINDIR/
/System Volume Information/
/MSOCache/
/I386/
/Documents and Settings/All Users/Application Data/
/Documents and Settings/.*/Cookies/
/Documents and Settings/.*/Local Settings/History/
/Documents and Settings/.*/Local Settings/Temp/
/Documents and Settings/.*/NetHood/
/Documents and Settings/.*/PrintHood/
/Documents and Settings/.*/History/
/Documents and Settings/.*/NTUSER.DAT/
/Documents and Settings/.*/Application Data/Mozilla/Firefox/Profiles/*/Cache/
/Documents and Settings/.*/Application Data/Opera/Opera/profile/cache*/
/Documents and Settings/.*/Application Data/Microsoft/CryptnetUrlCache/
/Documents and Settings/.*/Application Data/Yahoo! Desktop Search/
/Documents and Settings/.*/Application Data/Google/Google Desktop/
/Documents and Settings/.*/Application Data/Microsoft Help/
/Program Files/Microsoft Office/Clipart/
/$Recycle.Bin/
/ProgramData/
/temp/
/tmp/

EXTENSION EXCLUSIONS

.bak
.dwl
.dwl2
.atmp
.laccdb
.swp
.temp
.tmp
.tmp$
.ini
Thumbs.db
.DS_Store

in Filecloud