You should defintely go the route of doing your own mobile stuff. Do deals once you have your mobile stuff to be promoted on operator portals etc. Mobile advertising is young but there is some stuff out there (admob.com). I run a site about high end mobiles and although traffic to the mobile site is perhaps 5% of that of the main site it is still significant. There are a lot of things to conisder though (which device you target, whether you go for an all or nothing strategy in terms of device support). Personally my advice would be to go for the low hanging fruit intially (i.e. phones with better browsers) - look towards XHTML MP.

You should also bear in mind RSS is increasingly being supported on phones now. There are going to be some 75m phones shipped this year that support RSS out of the box. However it makes a lot more sense to have mobile specific RSS feeds that point at sites optimised for mobile. I wiil not go on here for the sake of brevity, but people interested are welcome to contact me (rafe at allaboutsymbian.com).

Sorry I think these might not be are UIQ 3 (depsite what I initally thought). Got my model / code names mixed up a bit.