Regularly seeing .Mobi sites advertised.
The mobile registry has the right to bestow one and many two character domains for free to the company they believe will best help advance the mobile web. (they are first to get this ability, among the gTLDs.) A solid deal with Google to heavily promote G.mobi and one with Yahoo to promote Y.mobi would probably create the mass awareness that the extension needs. Both are realistic, IMHO, Google paid $1 Million for G.cn (China) and Yahoo is calling itself "Y! mobile" on it's mobile version.