As of September 2011, the improvements on the road from Zugdidi to Mestia were completed, the road is now widened and paved allowing for travel by marshrutka (minibus) to Mestia, in much less time, two hours or less. There are also plans to improve the road from Mestia to Ushguli, though I don't know when this slated to happen, or if it has already. I stayed with the Ratiani family in Mestia, and they were very helpful in arranging transport to Ushguli. In Ushguli, to save time/energy you may consider renting horses to carry you and/or your gear to the foot of the mountain.. this is very inexpensive. Happy travels!
"After the first glass, you see things as you wish they were. After the second, you see things as they are not. Finally, you see things as they really are, which is the most horrible thing in the world."
--Oscar Wilde on Absinthe