Today we've added a "Print Thread" package that allows you to print directly to PDF the full contents of a thread (up to 100 messages long). Each thread - and each post as well - should now have a "PDF" button at the top right to allow this option.
Due to the variations in themes and screen sizes the output is reformatted so it's possible some formatting aspects are lost, but the result looks pretty good and works well. I don't see that the package has any options I can change, so the result "is what it is" but I think this will be a useful addition. If anyone has any problems with it let us know!