We've had this discussion before some place else. GPL that requires source distribution is excluded from the market, not use. IMO, big woop, wanta fightaboutit?

Since when does GPL software care if it makes it on MS's home page? Windows doesn't have repos.

In that discussion I mentioned I found no evidence either way about installing 3rd party software, all that is mentioned is that for use with Market developers must submit software. One assumes a devel can write, compile and sign anything one wants. Even in beta, WP7 allows a (limited) number of unknown software. At the very worst, it will be jail broken, like all successful OSs (haaaa....)