TwitterBridge
I've enabled the TwitterBridge plugin on my StatusNet instance a couple of days ago and following the instructions in the README got my notices pushed over to Twitter, but importing my Twitter-friends tweets into my StatusNet timeline didn't work.
When running 'scripts/startdaemons.sh', I would get:
Fatal error: Uncaught PEAR_Exception: DB Error: no database selected in unknown on line unknown DB_Error: DB Error: no database selected in unknown on line unknown
Searching around, I found a couple of threads suggesting to change "mysqli.reconnect = Off" to "mysqli.reconnect = On" in the "php.ini" file used by PHP but that wasn't working for me. What seemed to work was changing $config['db']['database'] from 'mysqli://[...]' to 'mysql://[...]' in StatusNet's "config.php" as suggested here.
I'm not exactly sure what this changes in the backend, but everything seems to be working okay.
2012/04/15 Update: I've also applied these two patches by @jbafvre