I just configured the gogo client on my Ubuntu Maverick and everything works like a charm.

Here is a short guide on how to set up the client on Ubuntu:

1. first install the client with sudo apt-get install gogoc (the tspc is deprecated)

2. modify the config file from /etc/gogoc/gogoc.conf with sudo nano -w /etc/gogoc/gogoc.conf.

Locate and modify the following lines:

userid= your_freenet6_id
passwd= your_password
server= broker.freenet6.net

3. start the gogo client with sudo /etc/init.d/gogoc start and you are ready to go.

4. try a ping to ipv6.google.com (ping6 ipv6.google.com)

Hope this is usefull.
If you are interested in IPv6 connectivity and stuff go to gogo6.com IPv6 community

Cheers