This is a quick overview based on only an hour on each system.
Strangely, on the 360, there do appear to be some texture issues from time to time, even playing from disc, which seems to support Bethesda's update that this is not a HDD issue. When the textures look fully loaded, the quality is excellent, but in some instances (I noticed 1st person weapons and a table in one instance), the colour looks slightly washed out and almost missing a top layer of detail. Landscape/environment details are absolutely fine for me and look great.
On to PS3. The colours seem slightly brighter to me overall, and I don't think it's a tv issue. I have not seen any texture issues at all, and no lag, although I do have one of the newer slimmer 320g consoles. One point I will make, is that the water effects, such as streams/rivers on the PS3 are outstanding

Overall, I do feel the PS3 looks slightly better at the moment, but I have not played it anywhere near long enough to know if we will get some more bugs on this platform over xbox 360. My gut feel is that when fixed, there will be little between the two systems when I compare what appear to be fully complete and loaded textures (apart from that water!). Given I have the luxury of both consoles, I am going to do a first play through on the PS3 and join the Stormcloakes, then a second playthough on the Xbox and join the Empire. At some point in the future I will do a much more detailed comparison.
I hope this helps everybody!