.mobi domain names are not only sold by net4india, but by directi and me too
But IMO, this is not the right time to go for it, unless you have a great plan in place.
Existing content can be duplicated, but you have to re-code the pages in most cases.
Anyone (including you and me) can design web-pages for a mobile phones. Go to
http://www.w3schools.com and have a look at WML tutorial
They can be hosted in the same way as other web-sites on a linux/windows server.
Just to try, I have made a small WAP site long back on my hosting space. If you have a GPRS capable handset and you have got it enabled from your mobile service provider, you can go to the following page through your mobile phone.
http://www.mailnspace.com/mobile/pics/index.wml
It just contains some 128x128 wallpapers for mobile. If you want to preview those wallpapers through your comp, you can go
here