Well yeah, but it isn't specific to registry or even to Windows, you could get that with pretty much any extensible system. In Window Maker, for example, you can set up the application menu to use a dynamically filled entry so i wrote a shell script that scan my Steam folder to fill the installed games. Any mistake there could have had a similar outcome (e.g. launching Steam every time i right clicked on the desktop or generating an endless .\.\.\.\.\.\.\. list from not skipping the . directory or whatever). KDE and GNOME have many extensions and people already complain about GNOME's performance when it comes to shell extensions.