Hold on, does Ubuntu for Android actually run on anything? Last I heard it was in deep alpha.
64MB, sure, that's pretty tiny for a desktop (though i doubt you'll enjoy using Gnome with that much ram, but sure, it'll run).
But note: the Ubuntu Edge has 4MB (wow, did I screw that up; it has 4GB, which is of course more than enough — the rest stands) of ram, as in 1/16th of that.
The thing is, Ubuntu got where it got by exploiting extant resources and making them user-friendly. There's nothing wrong with this, of course; i like Ubuntu. However, there simply aren't a bunch of open source projects that Canonical can slap together to make a user-friendly smartphone. It would take real engineering by Canonical and afaik they haven't done this before, which doesn't inspire confidence.
I wish them the best and I hope it works, but I'm glad it's Canonical doing it. If they do screw it up, there's a decent chance that the backers can sue for their money back, as opposed to a smaller player.