The FT plays with ad-supported mobile content. I hope someone starts releasing results for this sort of thing; whether it works or not, we're so early into the industry that it'd be good for everyone to know.
Hmm, actually - maybe this is one advantage of the Java portal route, which I'd not considered before: complete control over advertising sales and the like from within your application, and the means to flexibly alter and play with this. Oh, and not have to cut the revenue with an operator.
Not sure I'd agree with Carlo that "FT and CNN deals do suggest that it's possible to create ad-supported mobile content that is non-intrusive and acceptable", though. There's a significant difference between putting a commercial deal in place to do this sort of thing (which is not to downplay the work that's necessary there) and building a service incorporating this deal which both advertisers and customers will find acceptable.