I was asked on Twitter by @nambor why .tel couldn't be replaced for free by an hcard microformat on your domain (see the tweet here.
Well, let's look at the problem at hand, namely: how can I access your latest contact info when I need it to communicate with you?
That is the fundamental problem that .tel and many others want to solve. And solving it is possible, but a number of prerequisites are necessary:
1. Your contact info needs to be always accessible
So you need to put it somewhere I can get to, which means on the Internet. And it needs to always be in the same place, which means that you can't rely on 3rd parties. You need your own domain.
2. Your contact info needs to be understandable by my dialer program
It's got to be in a standard published format.
3. Your contact info needs to be up-to-date
You've got to be able to quickly and easily update it.
4. Your contact info needs to be protected with strong privacy settings
You probably won't want to give your mobile number to anyone. Therefore you need some kind of identification of incoming requests, and a strong privacy layer on top.
Storing an hcard microformat html document on your website solves point #1 assuming you've got your own domain and website. Incidentally, not having your domain means that you're at the mercy of a 3rd party who might cut you off due to it failing or raising prices to unacceptable levels, which would force you to change the location of your hcard, thus breaking the "always accessible" rule.
The hcard is a good standard and sloves point #2, but for #3 and #4 you'd need to build your own update and privacy infrastructures. While updating an hcard on your domain on the move could be done with some work, a proper privacy layer that doesn't break standards (point #2) and is easily accessible (point #1) is very hard work.
So let's recap the hcard solution: you need to pay for your domain (any .com or equivalent will do) and a website, you need a means to easily update your hcard even when on the move, and you need a custom-built privacy infrastructure that you hope will be accepted.
Well, for about $1/month and a 5 minute setup, anyone can have a .tel that will do all of the above and much more. You don't need another domain, you don't need to build anything, and you've got free apps for all major mobile phones and Outlook. Oh, and you can have your vcard for free too (we'll add in hcard if it's requested by the .tel community).