Halo is coming to a mobile device near you. Frankly if it doesn't have a multiplayer like Xbox live then it can f----off, otherwise blowin-the-shi@t out of strangers could be fun on the go. I never was too much into the campaign mode!
It will be interesting to see how it translates, and when it will become available. I imagine it won't be for a year or two, unless they launch a dedicted mobile hardware device, which would sell like...well....Halo2.