I saw the OSC Inventory application over at sourceforge.net. OSC Inventory keeps a database of a computers configuration (applications / hardware installed) will run on Windows or Linux and supports clients running: Microsoft Windows 95/98/Me/NT4/2000/XP/2003, Linux, Mac OS X,Sun Solaris, and IBM AIX. It is also released under the GPL license.
Their website also includes a very good explanation of the GPL license for people unfamiliar with it.