Can I change "Activities" in gnome-shell to an Ubuntu logo?

I'm looking for that also. If you check back in at this site:

Gnome-Shell Extensions

You will see a note stating that he will be updating his extensions to work with 3.2 over the next few weeks.

Go into the 3.0 extensions link and you will see an link for activitiesbutton.tar.gz

That is an extension that allows you to select an icon to replace the activities label in gnome 3.0, but as yet I haven't been able to recode it successfully myself to work with 3.2, so am waiting on fpmurphy to do it ;0)

If you have any more luck with it please post back here and let me know :)

Cheers!