I to would like to see Google come out with a Mac version of "Picasa".
I have several thousand photos that I would love to have all in one easy to use browser/editor, but iPhoto takes so much memory/time, etc. that RapidWeaver (a great/cheap/easy website building tool available at realmac.com) eventually crashes if I have iPhoto open when I am editing a multiple page site.
Meanwhile...
The solution that I have found is a small app that allows you to create multiple libraries, and only open the one that you want. $10.bucks (free trial version also available at link below), seems to work pretty well. Get it here:
http://regnault.luc.free.fr/softwares.html