Zedomax blog has a preview of an Android tablet running Android at the Adobe exhibit at Web 2.0. Although the preview shows off a lot of the functions (including the ability to run Flash and Air applications on the tablet), there are two distinct disadvantages for an Android/Flash tablet:
The number of apps available for Android versus the iPad
Currently Apple has more than 180,000 apps, versus Android about 50,000 apps. I hate to quote Balmer, but "Developers! Developers! Developers!". If I have a platform where the 1 millionth device just shipped, versus a new platform, I'd go with the 1 million device user base.
The different user interface a (touch) tablet requires versus a mouse drive app.
Examples of this are hover functions, double-click, etc., which have to be redesigned for a touch interface.