Facebook and StackExchange have both recently changed how comments are handled.
Users enter text in what appears to be a textarea. When they press enter the comment is now submitted. Using shift-enter will insert a carriage return.
Previously enter inserted a carriage return and a separate button is used to submit the comment.
I'm interested in expert views on whether this is good or bad for usability - should other sites be adopting this approach or alternately explicitly rejecting it?
Details of the background to the StackExchange change: http://meta.stackexchange.com/questions/63303/why-can-you-type-new-lines-in-comments-if-they-are-never-rendered
I can't find similar discussion from Facebook about their change.
EDIT - some additional thoughts. People have mentioned not noticing the change in SE - I wonder if this is because the submit button has also been retained. In contrast Facebook have removed the Add comment button, so it is more jarring to users as you stop writing and then think 'how can I submit this?'
It was also pointed out to me that Facebook does explain about using shift-enter for carriage return, but only after the user has already pressed return in a comment and then subsequently deleted the comment.