Architecturally, Moblin and Maemo also serve two very different ends. Moblin is heavily targeted at Atom while Maemo targets ARM SoCs (TI SoCs in particular). These are two very different beasts with very different requirements for good battery life and good performance.

Both platforms are quite different in their goals and execution, so I can't see a merge happening at any point in the near future. Software compatibility, perhaps (although Intel's utterly bizarre move to Fedora makes that less feasible), but a platform merge, no.