You're actually asking about panoramas, rather than photosynths, but in any case there is nothing announced for exporting your panorama cube maps from Photosynth.net.
If you simply wish to copy out the files which comprise your panoramas' cube maps, then you could use an unofficial utility such as iExplorer to browse your iPad's file directory and copy all of the Photosynth app's data. The problem then is finding a utility to open the cube maps or convert them to a format that another panorama viewer can read.
Out of curiosity, why do you consider uploading your panoramas a difficult way to share them? If you were emailing them to others or even sharing them over WiFi, wouldn't it just be simpler to send a URL to your panorama here on the site to another person and have it automatically open in their web browser?