300MB of photos and 2 videos per month
15MB/photo; 150MB/video or 20MB/photo; 500MB/video with a paid plan
Allows flexible public and private settings.
Not as easy to use as Picasa, particularly for uploading or editing, but has a larger and more passionate user community
Web, desktop (Windows and Mac), iPhone, BlackBerry
Only allows sign up through Facebook; encourages social sharing
Integrates with links, commenting, videos, and notes; perhaps a more innovative photo sharing experience