BuddyPress.org

I’m sure it is possible to update both using some javascript. Twitter essentially does this on your homepage when you’re logged in. Javascript is not my strong suite so I couldn’t say for sure. As far as setting a character limit for you status updates, you would use the ‘bp_activity_content_before_save’ filter located in the BP_Activity_Activity::save() function, in the file bp-activity/bp-activity-classes.php.