If you get a short text message about "Your request timed out. Please repeat the request." when you try to post, edit a post, etc. here is all you have to do:
Hit <F5> to "refresh".
It will ask you if you want to re-post the data (or something like that). Click YES by all means, and your post will be saved!
It's happened to me twice this morning, but I didn't lose one letter of any of my posts, following the technique above.
Edit: Make that three times. I had to follow my own advice as I created this topic!
Apparently there are some widespread Internet problems going on. Maybe it's all just a coincidence.