Google has added a search box to the Picasa Web Albums login page – which is less useful than it should be because being it causes a security popup in Firefox every time it is used (since it's a secure https page trying to send data to an insecure http page).

Of course, you can usefully add the same code to any other (http served) page, which is exactly what I've done within this blog post:

http://www.zmarties.com/picasa/blog/2007/04/searching-picasa-web-albums-without.html