There IS a solution...
Not all NAS is FUBAR with Time Machine. It seems (from the scuttle on their forums) that the new NAS front end for the Drobo (DroboShare) which was just announced at MacWorld does work with Time Machine. SO, there is a good solution out there that doesn't lock you into a single drive embedded into your router (which sounds like a recipe for disaster!)
Biting the hand that feeds IT
