Yes, I have an '08 800TSV and I run it at its native 800x480. Xenarc's website specifies a very specific set of signal timings to get the exact native resolution through a program like PowerStrip. Both my computer and LCD refer to this resolution as 800x480.
And I tested that it truely is native by setting my background to vertical and horizontal one pixel wide black/white lines. No moire patterns. (Tried the '08 Lilliput 7" widescreen just previously and returned it because no amount of timing tweeking could get a perfect 1 pixel to 1 pixel resolution)
Have you tried the magic timings & xenarc's website?