Long time ago I've heard (from digg/slashdot, I forgot which) a plan to release VB6 as open source which later denied by MS staff. But now I found this: http://sourceforge.net/projects/dvb6
It is a real full GUI VB6 (by microsoft) with "about" dialog still showing serial number (lol) but mention new license under GPL-3 (hmm.. they usually using their own Public License). Suspicious sources also available (more like a decompilation though) and as expected it's 32 bit only, not that there is a free 64bit compiler anyway.
The installer also bundling unregistered version of Bytessence InstallMaker and famous Angus' Resource Hacker.
The project already generate thousands download/week since 10/10/2012