Well, the issue is less ARM-compatibility (Cortex A8 is armv7, ARM11 is armv6, one or the other is just a recompile away—and, fwiw, Debian is armv5 and works fine on OMAP2 and OMAP3) than all the extra features that might possibly be thrown in. Interface compositing with PowerVR, a RAM boost, much faster CPU. Basically, it's a similar situation to what happened with the 770. Nokia did promise us at least 2 rounds of support per tablet, and the N810 has only gotten one (no, the dinky little Diablo update does not count as a round). So either Nokia breaks the promise (I picture rioting here) or, as Jaffa put it "hamstrings" the backport to keep it within the OMAP2's limits.