I work on Hecl (http://www.hecl.org), but as an open source project. I think a language is not the best idea for a startup, as it's something that can gobble massive quantities of time and brainpower[1]. Their (tsumobi) idea for downloadable apps is good, though.

I think it's a fascinating space, in any case. Sooner or later people are going to start getting it right. I wrote up some notes on what I think "getting it right" means right now:

http://journal.dedasys.com/articles/2007/05/03/cell-phone-software-the-right-path

[1] I seem to recall reading about a certain well-known individual who has a neat idea for a language that still hasn't seen the light of day after years, although it's rumored to power some kind of news site.

you mean mobile apps or mobile services?

we (heysan) are building a mobile messaging services, but the guys at iminlikewithyou have done a great mobile integration too.