Let he who has never made a spelling blunder cast the first stone. Earlier, I was posting from the default Firefox in SL 6.1. Expecting it to catch my speeling errors inline. I made several posts before realizing that the damned thing was completely nonfunctional, and was too mortified to go back and look.
I'm in Chrome now. And it caught "speeling" quite handily.
RickMoen mentioned something about a "sixty second window" for LWN.net posts. I've never noticed any sort of window at all. As soon as I hit "Publish comment" my mistakes are frozen for all eternity.
Sometimes it's a comfort to know that no one really cares about my posts. ;-)