I like the alternatives system in general, it doesn't give me headaches, it does it's job quite well, and it's pretty easy to configure. This is a general approach though, which should continue outside the control panel too. (Browsers, galleries, etc.) On the other hand I really hate when applications try to hijack basic functions, so this system must be securely opt-in, so no rude postinstalls can force the newly installed phone application to take over the default.

By the way, two new articles are over there @Grog.