Yes, there are ads. If you read Shaun's blog here
http://blog.smxy.org You'll see that the largest installer repository has had some issues with the previous hosting providers, basically pulling the plug.
We (Polar Bear Farm) along with another sponsor FreeIt4Less.com have provided some security of hosting by donating a couple of servers on dedicated connections to support the several terabytes of data used by iPhone users very month.
The alternative to this would that the largest repository would not longer exist, as it's not cheap to deliver that sort of bandwidth reliably. You'll also notice that source refreshes are now substantially faster.
Layton Duncan