what exactly AmigaAnywhere is
AA is an AmigaDE derivative.
AA/DE content is usually platform independent, like for instance Planet Zed being demonstrated, running on both Linux and PocketPC powered PDAs at the WOASE show.
The "Paks" Microsoft will be distributing will only include a PocketPC version of the AmigaDE derivative. So you cannot simply plug such a card into a Linux PDA, at least not without this PDA having the needed AA player pre-installed.
The PocketPC player is a couple of megabytes big, small enough to bundle with 4 games. Ideally target devices would all have the needed AA/DE player pre-installed, as you would then have a couple of spare megabytes on the card to use, and you could easily plug any AA pak into any AmigaDE compatible device, just like Bill demonstrated on the TechTV show.