I'm currently developing a Google Reader Notifier for linux (check it out at http://grnotify.sf.net if you're interested), and need to be able to open the users default webbrowser and login to google reader automatically.

I currently do this using the webbrowser module, and then using the command webbrowser.open("http://google.com/reader").
But this just sends the user to the google reader homepage, and doesn't log them in. I would like to know how I can open the user's default webbrowser and send him to a site with post parameters? Or is there any other way to login to google reader, thus without using post parameters?

You would have to figure out how google has their cookies. Basicly you would need the user to enter acount and password and create a cookie and put it in the cookie for the webrowser or os (Im no expert here...). Then you would use the webbrowser.open() module.