Why Did Georgia Attack South Ossetia?

Two weeks ago,  in my first substantive entry, I suggested that the only way to understand why Georgia had risked going to war was if Russia had deceitfully led Georgia to believe that Russia was prepared to let Georgia regain control of South Ossetia.  

 Today the New York Times reports that Georgia is making a case of provocation almost entirely opposite to the scenario I speculated about.  The articles states that over the past week Georgia has been informing allies about intercepted Russian phone conversations that suggest Russian troops had actually moved into South Ossetian territory before Georgia went on the offensive.  The Russians, not surprisingly deny this.

I have no idea about who is telling the truth here, and it is fine with me if my own rampant speculation is eventually proven false, but I'm not yet ready to concede I was wrong either.  At this point I would like to know why Georgia found these troop movements so troubling.  From what these documents purport, however, I think  that even if entirely genuine they will not exculpate Georgia as much as Saaskashvili would like.  It still seems implausibly rash for Georgia to react to just the reported Russian troop movements into South Ossetia by attacking South Ossetia, unless there was something else that made retaking South Ossetia a real likelihood.  Admitting to rashness, however, will not win many converts to Georgia's speedy accession to NATO, so it will be some time evidence crops up that definitively proves Georgia's leaders acted rashly either out of fear or because they believed false intelligence.