I'm on hardy and have the same problem: message pop up, but nothing appears in the gwibber window itself. I followed the install method listed on
https://wiki.ubuntu.com/gwibber
from repository.
I also tried the other gwibber installation methods posted online for hardy and all gave errors.
SOLUTION:
Ok, after a few hours of questionable time spend fishing around to play trial and error this worked for me. This installs an older version of libwebkit, and a 0.7.3 version of gwibber.
First remove the old files and repositories first then install these three DEBS:
http://ppa.launchpad.net/stemp/ubunt...yppa2_i386.deb
https://launchpad.net/%7Ejorge/+arch...~ppa2_i386.deb
https://launchpad.net/%7Ejorge/+arch...~ppa1_i386.deb