It is very difficult to debug with the information you have provided.
The webbrowser.py has indeed undergone some changes, but they are
positive changes and should not break any working behaviour.

For your problem, you might want to mention.
1) Your OS.
2) Your Default Browser ( as set by the OS)
3) Also, do the webbrowser.open() on a generic site like
"ftp://ftp.aduni.org" in your python2.6 installation to see if that
works.

It works for me in python2.6 + firefox 3.x + Ubuntu.