Hi Scott,
For awhile now I have noticed that some users posts are pushed off to the right (including yours). In IE7 it all still looks good. Unfortunately I wasn't really paying enough attention so I don't know if this started right after the release of IE8 or if it was an update.
The offset is not the same for each user. The offset seems to range anywhere from an inch to off the screen. I'm guessing the offset is related to the avatar. At first I thought it was only happening to those who have avatars that are wider than they are tall, but that doesn't seem to be 100% true.
Here are some other users that I see having the same issue:
NoHeart
honeylee04
DOC (his posts are off the screen on the right)
Hatsuyuki
Sophieka
samz1440
HezEX
GodDream
angelcaptor
Kurune
Andrams
Hasui
onxblaq (this one is way off the screen too)
Level 156 fire
T4
90% of the laws are made because of 10% of the people.