I've been very frustrated with the way Picasa displays my panoramas. The down-sampling sucks, but even if I upload full resolution panoramas, unless you download them to your PC, you have no way to scroll, click, and zoom through the panoramas.
Then the other day, I noticed that PhotoSynth has been integrated into Microsoft ICE. ICE is what I use to composite the images. There are other free tools available, but none are as easy to use as ICE. PhotoSynth, however, is the other half: it solves the viewing problem by allowing the user to pan, scroll, and even zoom in through a high resolution image. Apparently, you can even use it to take a picture of a room from all angles, and PhotoSynth will create a model and let you walk around through it virtually. This is very cool stuff. Yes, it's 100% Windows only (did you expect anything else from Microsoft), but it definitely shows off my Panoramas in full glory. After you've clicked through on the above, visit my Synth Gallery to see all the others.
P.S. Here's one from last year: