Somehow, Hasbro seems to have complete rights to every character created for the G.I. Joe comic. On the other hand, they don't have the rights to Circuit-Breaker, who was created for the Transformers comic. My understanding is that Marvel specifically decided Circuit-Breaker showed some promise, so they debuted her in an issue of Secret Wars II before she showed up in Transformers, and somehow this makes her Marvel property. This is why IDW's Classic Transformers series is missing issues -- they had to cut out all the issues featuring Circuit-Breaker (and because the series is incomplete, I refuse to buy it!).

Also, for the record, G.I. Joe being a licensed property has nothing to do with their lack of interaction with the Marvel Universe. Remember, Spider-Man appeared in Transformers #3 -- and in the 70's, Marvel had several licensed properties that did interact with the Marvel Universe: Micronauts, Shogun Warriors, Godzilla, and ROM: Spaceknight are four that I can think of off the top of my head. I suspect it was Larry Hama's choice (or possibly editorial's) to keep the Joe world separate from the Marvel Universe. I doubt it was Hasbro's idea, due to the Spider-Man/Transformers story I mentioned, and the fact that ROM, another Hasbro property, was a major Marvel character for several years.

As a side note, back in 2007 Marvel teamed up with IDW to do a Transformers/New Avengers crossover. Truthfully, it was just Marvel trying to cash in on the Transformers money train that was about to take off, because it was released around the time of the first movie.

The funny thing about it is that this story is supposed to be in the normal continuity of both series disavowing Spider-Mans previous encounter with the Transformers.

For all who are interested heres the Wiki link.

This is probably the best explanation as to that type of thing: http://treasuresntoys.com/webcampoktoberguard.htm

I seem to recall, way back when, reading a letter to the editor in either the one and only Joe comic I ever read, or, more likely, in a Punisher comic, where one of the readers asked why Frank Castle never joined with the Joes for a mission and the reply was that because of the nature of G.I.*JOE and the whole Hasbro thing, that they couldn't do crossovers.

Interesting. I know there was a letter in a latter-day G.I. Joe issue where someone suggested Wolverine teaming up with Snake-Eyes, since Hama wrote both titles, but I think their answer was just that the G.I. Joe universe is separate from the Marvel Universe, but I don't believe they went into any more detail than that.