mobile is def something to get involved in now if you plan to. there are currently over 4billion cell phone users on the planet. not all smartphones yet of course but that will change over the next couple of years. point being,,,more people will be reachable via a cellphone than any other media format in the history of mankind. more than radio, tv, newspaper/magazines, anything. over 4billion. thats over half of the planet. and you all know numbers rule. think about it, if you got a sale from .0001% of 4billion, thats a six figure income. i agree it is a good time to pay attention to that. and if you cant convert .0001% of your traffic than your in the wrong biz anyway. imho.
but to answer the question, i have not done anything to make my site mobile friendly at this time, as most smartphones will force the adjustments. but it i agree the time to get on it is upon us. good topic.
also there is alot of money in the apps. i have not looked into the iphone personally because apple has to approve everything so might be mmore of a pain in the ass, but android market is open to everyone and you can find developer info at
http://developer.android.com/guide/index.html
good luck everyone.
-abatis