Does Ubuntu 11.10 use the new version of Gwibber? Then why is that feature (to write to all the accounts I have at the same time) not available? Can someone help to bring it back? More importantly, how can I set the refresh time in Gwibber to 1 second?
Gwibber got an update for Ubuntu 11.10, and not all the old features made it to the new version. It's a big improvement overall but it is still a work in progress.
You can report bugs or ask questions on their Launchpad page here, or just wait for the next big update in Ubuntu 12.04.
Setting the refresh time to one second is not possible, that's because of rate limiting by Twitter. It has nothing to do with Gwibber. If you somehow set this anyway, Twitter would just return errors after about 350 requests/hour, or less than six minutes. More info on that is available on Twitter's rate limiting FAQ page here.