ecos (e.g. redboot uses this OS) has a synthetic frame buffer, which pretends to be a framebuffer but just goes to a window at an X-Server.
Such a device on maemo would allow running android in parallel to maemo , as the main obstacle of android on maemo is that it needs a frame buffer for its own.
But it seems that qt already offers a virtual frame buffer - qvfb, which could be ported to maemo and minimize the work a lot - http://doc.qt.nokia.com/4.6/qvfb.html