Haven't used Picasa but have browsed it. Flickr seems more community based and Picasa is just storage. I haven't used the MobileMe either, so can't comment on that.
I use ferrarilover355 account occasionally, but mostly cdn4re. http://www.flickr.com/photos/ferrarilover/ Chris
Circulating through the corp intranet: http://www.flickr.com/holidaygift http://www.flickr.com/holidaygift http://www.flickr.com/holidaygift
not to gravedig, but just throwing my name in here. Love these cars, and loves seeing great photos of them Ravi Gill Photography's photosets on Flickr