The OS itself can be updated on your own. See
http://www.xoutpost.com/navigation-sy...available.html for links to download the latest version.
Also see
http://www.xoutpost.com/articles/all-...ystem-faq.html
As for updated navigation maps, you can get them from
http://navteq.com - that will run you $200. You can often find a copy that is a year or two older on eBay for less. Just be sure you get one for an i-bus based BMW.