Facebook has a 420-character limit on status updates, fwiw. Obviously more than 140-char, but I've been annoyed at times when I've wanted to post something more in the high-400s range.
Probably just the ADHD, but I find myself running past this limit all the time.
What really annoys me about it is that they don't limit the characters in the text box - you can happily paste a novel in there if you want. Just when you go to post, an error that you're over the limit (at least they do say by how much).
It's clear that they use JS on the box (if you don't wait for the page to load, the box won't auto-expand as you type) - why they don't implement a simple script to stop typing beyond the limit is beyond me...
>why they don't implement a simple script to stop typing beyond the limit is beyond me...
I'm thinking that once you've written out the text you seek some place to post it and so this sort of thing increases interactions on the site, after all you're already there - you make it into a message to several friends or start a page about it or whatever. Alternatively people put it on a blog and then link their blog into their profile in someway, again increasing the information available on that person, strengthening interactions and widening the link graph.
Because when I hit the limit I want to finish my sentence and then edit down to 140 characters, not be forced to edit down straight away and forget how I was going to finish my point.
I like twitter's solution of letting you type past 140 but giving you a visual indicator that you're over the limit (and a letter-count). Facebook gives you no feedback at all until you hit submit and get the "too long, jerk!" error message. Then you edit down a bit, try again, it's still 3 letters too long, etc.
I could see them not having a letter-count display shown by default (since most statuses are comfortably <420 chars), but it'd be nice if a "20 chars too long" thing appeared below the text box once you started typing too much.
