Looks like Russia has been planning for trouble for some time. Special Railroad repair troops upgraded rails in July, Kavkaz-2008 military maneuvers concluded last week on Abkhazi/Russian border and Russian paratroopers deployed at Roki tunnel.

Looks like Ossetia setup Georgia for Russian counterattack including Abkhazia flanking maneuver.

http://jamestown.org/edm/article.php?article_id=2373276

Georgia has withdrawn from Ossetia according to BBC. Georgia has asked for a ceasefire but Russia has not responded. Russian intentions should be clear within the next few hours.