I recently noticed that Slashcode.com does not show
signatures in comments. I confirmed that the "disable
sigs" checkbox was not checked in my preferences, and
still could not see sigs in comments. Even testing
from a non-logged-in browser (anon coward), I did not
get signatures with comments. While I can't be sure
about other users, my account (kill-hup) does have a
sig specified in my preferences.
Unfortunately, I can't tell how long this has been
happening. I only noticed it today.
Hope this helps.