Google announced a beta release for offline viewing of photos on the Picasa web site using Google Gears.
Picasa Web Albums for Windows Mobile
This release only works on Pocket PC type devices (Classic and Professional Editions). I tried it on an HTC Advantage 7500 running Windows Mobile 6. Google Gears installed fine on the device. But Picasa could never seem to get into an offline mode. It kept asking to connect to a network.
Still, it is interesting that Google continues to develop for Windows Mobile. I wonder if this will stop after the Google Android based phones are released.