Linaro isn't actually going to be a distribution as such, see the correction on the article you cite.

Also, MeeGo *will* be installable on the N900. It already is. It just won't be *commercially* supported, meaning you *won't* be able to ring Nokia Care up if you have problems with it, and nor will you be able to upgrade over the air. (But given it's a different OS, OTA upgrading wasn't going to happen anyway :P)