Yes, it is illegal.

Blender is aware of the problem by the way: http://www.blender.org/blenderorg/blender-foundation/press/re-branding-blender/

trueSpace 7.6, A7 commercial
Free gamegraphics, freewaregames http://www.reinerstilesets.de
Die Community rund um Spiele-Toolkits http://www.clickzone.de