Okay, the Kindle 3 on font size 3 setting (the default) displays 26 lines per page.
From this screenshot, it seems the new kindle displays 3 fewer lines per page on the same font size setting.
Since the panel is still the same 6", it probably means that they've recalibrated their font sizes to larger ones on the same corresponding settings. Which means fewer lines per page for those of us who read on the smallest font size setting to cram in as many lines as possible in a page.
Obviously it doesn't affect those that read on the larger font sizes.