I have tried the existing Picasaweb module http://www.silverstripe.org/archive/show/2174?start=0 and found it to be a bit wanting.
I also tried the image_gallery (and required modules dataobject_manager and swfupload)
Whilst incredibly powerful, the image_gallery still demands that user upload and sort their pics. This seemingly innocuous task is too much to ask of many non computer-savvy editors (and thats most of them I am afraid). Uploading to Picasa seems to be well within the grasp of normal users. Furthermore the bloat caused by the extra modules almost ground my system to a halt. Reloads of the editor could take minutes.
I therefore refactored the PicasaGallery.php to use jquery.pwi and you can see this working in very prelim form on http://www.boatshow.co.nz/boatshow-gallery/ Note that the users have not yet altered the titles. This is highly configurable and desperately easy to use and will even work with hidden galleries.
If anyone is interested I will upload it. Its only one php file and you can put a fresh jquery.pwi into /jsparty/jquery/plugins yourselves!!