Found a detailed topogrpahic map of Tbilis (unfortunately in Russian) that explains why the Georgians retreated and made their stand in Tbilisi. There is only one road into Tblisi from the North West. It runs through a very tight river gorge. The road is along the river. The Russians must be afraid of exposing their tanks to the (Israeli made?) anti tank weapons. So the only way for the Russians to take Tbilis now (besides a costly frontal assault through the river gorge) is to come from the South. So we could see some movement out west where the RUssian armor starts heading south along the main road. Obviously it would help if some bridges out west were wired for explosion. There are two roads coming from the south west into the south Tbilisi area. Should note that there is also a Russian military base in Gurymri Armenia. They could move their force of ~60 T70's tanks up toward Tbilisi and attack from the south. I am assuming they would be picked up however on the sats.
Here is the report of Russian Tank movement over night from the BBC.
Russian forces still control Gori, which lies some 15km (10 miles) from the border with South Ossetia.
Several tanks and armoured personnel carriers were seen in Kaspi, west of Gori and some 35km north-east of the capital Tbilisi - an advance of some 15km on their previous position. Lorries of soldiers were seen heading towards the town.
Meanwhile, Russian troops were seen patrolling in Zestafoni, some 100km west of Gori along a major highway.
Georgian officials also said Russian forces remained in the Georgian Black Sea port of Poti, the site of a major oil shipment facility, and a major Russian military contingent is further inland, at Senaki.
The crisis began on 7 August, when Georgian forces launched a surprise attack to regain control of South Ossetia, which has had de facto independence since the end of a civil war in 1992.
Last night a large armor group was seen going toward Senaki. Where are they now ? I heard they were heading toward Kutaisi. Were sure dont want to see them head south from there. 
Please note that the above map was made by the UN in October 2003 apparently before South Ossetia was an autonomous region.
The fight for Tbilisi is about to begin. That, or the Russians are engaging in a scorched-earth policy to decimate the Georgian infrastructure as much as possible before pulling back. I see no evidence, however, the Russians have any intentions of stopping.