ZD's Dana Blankenhorn identifies several reasons why various mobile computing initiatives have ultimately failed to generate momentum, and identifies LiMo as just the latest in a long line of initiatives that don't pass the test. He claims that the Mobile OS wars are "over" and the two winners/final competitors will be iOS and Android. A lot of it boils down to the control that the carriers have over the market, which gives the advantage to either very powerful players that can push the carriers around (Apple) or a well-funded entity who can give the OS away because their strategy doesn't depend on licensing revenue, or control of the end product (Google).
I'm not as certain as Mr. Blankenhorn that the mobile OS wars are over. The market is just too big, and it's pretty early. But there was a big opportunity for an open source mobile OS, and it just happend that Google came in early and came in hard, and it will be hard for another project, even one supported by large commercial entities to get a foothold, at least in the phone space.