The problem with self-hosting is a lack of visibility. Like Sourceforge before them, you basically need to host your project there for anyone else to notice it.
Of course you don't need to host it all there. Just mirror enough that it gets you the "visibility", while keeping everything else on your own servers.
Then again, there's inertia. And inertia always wins.
The interesting bit is that is about to get tested out with GitHub. Yes, of course, Skype target audience was network locked and not that savvy, but, the open source community does seem a tad bit different breed.
I think self-hosting is a better choice for almost any organisation. Remember, 'the cloud' just means 'someone else's computer.'