So far we've mostly been targeting iOS and Android for tablets, but there's another interesting tablet OS coming down the line -- Windows 8, which will run on both conventional PCs and tablets.
Windows 8 includes an HTML/JavaScript runtime for native apps using the new "Metro" style interface paradigm which is heavily weighed towards touchscreens, so we should be able to adapt the PhoneGap app or reuse much of its code.
I've been looking into what it would take to support a Windows 8 Metro style app well, and have written up some notes and screenshots: http://www.mediawiki.org/wiki/Mobile/Windows_8_Metro
A standalone test application that runs on Windows 8 Consumer Preview and implements some of the system integration (but none of the article reading!) is on my github account: https://github.com/brion/WikipediaMetroTest
There's also a preliminary solution & project file in the main app's git repo, in the WikipediaMetro subdirectory, but this doesn't fully run right now (the way we load some scripts violates a security rule) and doesn't do any of the integration. I'll try and get it running proper soon...
-- brion