I have 2 gifts for the new year:

A photosynth downloader which will let you backup your precious photosynth 1.
You can find it on github: dddexperiments/PhotosynthDownloader.

npm install
node synth_downloader.js 8645d183-4718-4325-bd7b-5d48955839d6 output

An updated offline viewer which support the photosynth 1 and view them with my experimental webgl viewer, created originally for my chrome extension.
The updated source code is available on github: dddexperiments/offlineViewer.
An updated win64 setup is available: Photosynth_Viewer_Setup_1.0.5.exe

BTW if you need a tool to get a list of ps1 to download, I would use the playground of the open-source photosynth2 viewer. You can select photosynth 1 filter (top right) and then use the file render method and csv instead of json for output.

Please checkout Nate post if you have trouble using the downloader.

Hurry up: you only have 1 month to download your favorite ps1/ps2!