Could someone built a Picasa Export Plugin?
 

any method by which I can upload a picture directly from picasa to PixePost. ?

I've checked into it a bit, and yes, technically, it should be possible, but It will definitely take some serious work to build.

If there is a great enough demand for this, I'm sure someone, maybe even myself will attempt to tackle it.

Inspiration:
http://picasa2flickr.sourceforge.net/

I'm game for this one too. Picasa is my main photo program with thousands of photos and it would be a great idea. I vote yes.