The pop in is shocking on the consoles in general. Playing PC on ultra has a ridiculously better draw distance than consoles.
Comparing a High-End PC to a console from 2005, I don't think anyone will argue with you on that point. Would it be the other way around than it would be a miracle.
I haven't seen the PS3 version myself but the HD comparisons make it look worse than X360: http://www.eurogamer.net/articles/digitalfoundry-face-off-skyrim
Two things are very noticable in the PS3 version (atleast in the recorded vids):
1. Jagged edges (easily visible when seeing any object with a background behind it (NPC with wall, etc).
2. Lower resolution distant landscape textures
Again, I haven't actually seen the PS3 version with my own eyes but I always thought it was a general consensus that the X360 version looked better. Around here everyone also seems to be angry at Bethesda for releasing the PS3 with so many technical issues.