Windows Live Photo Gallery Wave3 Beta has support for adding publishing support for 3rd party sharing services. So one can install available plug-ins and start publishing from Photo Gallery. So now such a plug-in to publish your photos to your Picasa Web account is available for Photo Gallery. This is created by Mark Steeves.
So this will add an option in the Photo Gallery
Add a plug-in option will also take you to List of available plug-ins.
As said these plug-ins only work with the new wave3 beta versions of Photo Gallery and Movie Maker, available here .