Got a little time to hack on this, even with my Python noob status. I got vim and grep, what else do I need?
I made a new profile for the 350 and got to work. First I started screwing around in NavBarTemplate and simply adjusted the "calibre_rescale" value to make the navbar bigger. It works, but it's not device specific and it looks ugly. Besides, Calibre does have a special touchscreen nav section, TouchscreenIndexTemplate, although it looks like Ipad is the only device that is using it now. I added "touchscreen = True" to the new 350 output profile.
I like the touchscreen news layout better than the default view. Unfortunately, some of the article links don't work right on the Sony compared to the calibre viewer. Also, the default behavior of the "Sections" link is Section Top, which is what I'm trying to get away from.
I'm going to open another thread specifically about this. I think getting touchscreen news nav working right would be a major improvement for the new Sony's.