Is there any way to make Gwibber respect the system proxy settings? Right now, if I try setting up a Facebook account from the "Broadcast Accounts..." option, it comes back with an "unable to load page" error.

Is there any way to make Gwibber respect the system proxy settings? Right now, if I try setting up a Facebook account from the "Broadcast Accounts..." option, it comes back with an "unable to load page" error.

This is a bug documented in launchpad:
You can use "All Settings -> Network -> Network Proxy -> Manual" and then after setting the desired proxy, "Apply System Wide". This way all Ubuntu's network traffic including Gwibber's will tunnel through your desired proxy.