Whenever I use the question/answer editor's link button, to insert a link, the link gets inserted correctly, but then each line-break is doubled (which means I now have three line-breaks between paragraphs, and single line breaks get empty lines = paragraph breaks.)
Repeating this doubles the line-breaks again, now I have seven empty lines between paragraphs. As an example, here is a screenshot from the editor of a question on the new crypto StackExchange (still in private beta), after inserting three inline links:
Actually, the same thing occurs after inserting an image (look at the source code of this question to see a single example).
This is happening since a day or two (I'm not quite sure), in Opera 11.50 on Ubuntu 11.04. (It does not happen in Firefox 5.0 on the same system.)