Failsafe method on Debian systems (should work on Maemo too but I haven't tried):
1. grep /usr/share/applications for the caption of your desktop icon (the path differs slightly in Maemo due to optification)
2. open the file you just have found and find the entry starting with "Exec=" - this will give you the actual program name
3. run apt-file search <program> to identify which package it belongs to
4.uninstall the package