From their website:

Sako is introducing the Brown Bear in action size XL. This widens the caliber selection of the Bear Series to include 416 Rigby, 450 Rigby and 500 Jeffery. The laminate stock has been redesigned to accommodate larger calibers and the barrel profile has been redefined for the new calibers.

Brown laminated hardwood,straight classic stock, black action and 540 mm semi heavy barrel (21,1/4"). Exellent balance for good pointability.

sako.fi or berettausa.com (US importer of Sako and Tikka rifles)?

I'm guessing that the price tag will increase appropriately. Whether or not it will be available in the US is another question.

You can look at it here:

http://www.sako.fi/sako85models.php?brown_bear

A regular Brown Bear goes for just under $2000 up here. I figure if they can keep this new one priced the same it should make for a decent, reasonably priced big bore.