Theoretically, it is possible to embed ads into a winforms app running on a smartphone, with .NET CF.
Is it practical to do? Are there ads available in "the right size" for the compact device"? How would I get topical ads? Will I get the volume of ad clickthrough that would justify the engineering effort? How would I get started exploring the possibility? I don't know ad servers, I haven't done ad-driven web apps.
Guidance?
Unless the ads were very topical, I don't think you could get a lot of people to click through an ad on their cell phone. The cost of data plans is so high, that I don't think anybody would want to waste their precious cell phone minutes to follow some ad. The other question is, where do the ads come from. You could package the ads with the ap, but that limits how many different advertisers you could have, and doesn't let you easily change who the ads are from. The other option is to download ads over the smartphone's internet connection, but again, I think this would create problems wasting precious bandwidth. Overall, I think it's a pretty bad idea. You should probably opt for a more traditional shareware type model where you give them a partially featured version for free and make them pay for the full version.