I was going to comment in bug #551326, which is a dupe of bug #530605, but as Brendan_P comments in the first bug, this doesn't seem related to samba or gvfs. This report seems to more accurately match my experience. Here's what I did to cause 100% CPU utilisation on Lucid:
Click the envelope icon and choose Broadcast
Click Close (didn't add any accounts at all)
The Gwibber 2.29.93 main window opened.
Do nothing; just click Close again.
Wait a few minutes and the CPU went up to 100%.
System Monitor reports the desktopcouch-service is taking most CPU