B4 you go crazy and give your cc a real workout, think about this. For mobi to take off, a lot will depend on adoption and standards.
Take goog for instance. gmail does not have a .mobi site; however, they (goog) took a different avenue by creating a mobile device subdomain for gmail:
http://m.gmail.com
I might be wrong, but a lot will depend on whether or not the big boys use .mobi and adhere to the .mobi standards.
While domain registration is cheap, the administration and re-development required to support the .mobi may not be worth it since 800 lb gorillas like goog already have a workable solution in place.
Just my 2 cents.
