[spokey]

I thought that went the other way: you need a patent license to author and/or run the TCK. You can create a Java compatible VM (many have) but you can't run the "official" compatibility test without Sun's, now Oracle's permission, and there is some concern (at least at Apache) that you cannot easily create a "cleanroom" implementation of that TCK. (Although I think that latter concern is more social than legal--if I remember correctly conventional wisdom said that there were too may Sun folks already involved with Java projects at Apache to have any reasonable expectation that a cleanroom would remain clean.)