Looking at the log, it looks like it is sending notifications. Or at least trying to:
2010-03-26 22:03:38,957 - Gwibber Dispatcher - DEBUG - Checking message 500404500_107868949241529 timestamp (2010-03-26 22:02:54.00) to see if it is newer than 2010-03-26 21:53:38.95 2010-03-26 22:03:38,958 - Gwibber Dispatcher - DEBUG - Message 500404500_107868949241529 newer than 2010-03-26 21:53:38.95, notifying
Can you look at the notify-osd log in ~/.cache/notify-osd.log and see if there is anything that looks gwibber related?
Looking at the log, it looks like it is sending notifications. Or at least trying to:
2010-03-26 22:03:38,957 - Gwibber Dispatcher - DEBUG - Checking message 500404500_ 107868949241529 timestamp (2010-03-26 22:02:54.00) to see if it is newer than 2010-03-26 21:53:38.95 107868949241529 newer than 2010-03-26 21:53:38.95, notifying
2010-03-26 22:03:38,958 - Gwibber Dispatcher - DEBUG - Message 500404500_
Can you look at the notify-osd log in ~/.cache/ notify- osd.log and see if there is anything that looks gwibber related?