I have not been on this site in a long time.. so trying to catch up. Mongoose Research, Inc is a vendor.. http://www.mongooseresearch.com
We won .edu style's award last year for top mobile site (m.champlain.edu).
Also, I gave a presentation recently on the topic... slides here:
Following up late on this discussion as well.
Frankly, I'm not sure I'd recommend working with a vendor on a mobile site. Doing even a basic mobile site isn't actually that big of an undertaking, especially if your normal site is already set up to be or adapt to a responsive layout. But even if it isn't, you can literally do a mobile site in under a week.
I present to you, PSU's mobile site. http://m.pittstate.edu/
Disclaimer, I no longer work at PSU, and I notice a couple things are unfortunately broken now. But, the important part is that I built that - using dotCMS - by myself, over the course of about 4 nights. Is it perfect? No. Does it do absolutely everything I'd like? No. But, it was lightweight, easy to put together, and easy to maintain.
And that's the crux of the problem. Say you spend $50,000 with a vendor to build your site. They make it awesome. But if you didn't have the resources to make it to begin with, how do you plan to keep it up? I strongly urge organizations to "live within their means," so-to-speak.