OK, I am more clear about Harmattan targeting platform, which invalidates my comments basically. Looks like I should send this kind of requirement to MeeGo project, esp. assuming Harmarran UI framework will be the base of MeeGo's.

Technology wise, I'd say it will be more flexible that compositor can "fallback" to use QWidget or even QWindowSurface(?) when GL support isn't available or at least provides compile time options. One example is KWin, which can run well with or w/o GL support.