Available now on many Nokia 5800 XpressMusic product codes, is a minor firmware update, v21.0.025, clocking in at 4MB over-the-air. To check if it's available for your phone, type in '*#0000#' into the virtual keypad and then 'Check for updates'. v21.0.025 brings interface speed enhancements, numerous bug fixes and a new 'breathing light' setting/control. Please comment below if you spot anything major that needs adding to this story!
As usual with modern S60 devices, User Data Preservation means that you shouldn't lose any data or settings. But it's still a good idea to back up anyway!
Previous mentions of this firmware have included references to improved camera performance, but I'm not convinced. Again, your comments welcomed.
(Thanks to Norman for spotting the 'breathing light' bit)