I had a quick look at the StrongARM SA-1110 docs last night...
Looks like you can set the vblank period to be anything from 1 to 64 lines
More interestingly, the chip supports 4 and 8bpp palettized modes!

If possible, using 8bpp could be a nice optimization for 3D engines!
And it looks like the base address of VRAM can be changed (must be 4-byte aligned - so no smooth 'hardware scrolling' though)
Can an app just write to these registers ( 0xB0100000 area)? Or is that memory region protected? Does the code that writes to them have to be implemented as some sort of device driver? (I've got no idea how that'd work on PocketPC)