As far as graphics goes, the OMAP2 chip inside Nokia tablets does include 3D graphics hardware, so the only problem is the drivers. I am pretty sure that sooner or later this problem will be resolved.
The LCD refresh DMA (=reading 800x480x16bits 60 times per second) would eat lot of memory bus bandwidth, slowing down everything inside OMAP. As for OMAP2420 the on-chip SRAM is still too small to hold whole 800x480 so there would be same problem. There are no public docs for OMAP2 chips but the TI page http://focus.ti.com/general/docs/wtb...emplateId=6123 says "5-Mb internal SRAM" (b stands for bits) = 640KB, good enough for 640x480x16bits VGA mode but not good enough for 800x480 (=768KB). Hopefully with new generation tablets the external controller will be gone.
Just order one from the US
Who told you that you can't expect a more powerful tablet? I only told you that you can't expect an OMAP3-based tablet by that time. But there is still a lot of things you can do with OMAP2 architecture, not to mention the system software (like those 3D drivers).