Terminal has what (I believe) is a new feature in 10.2: text can be selected in a Terminal window, and then dragged to any other terminal window -- upon release it appears at the cursor. Unfortunately, if a program like emacs is running in a Terminal window, the cursor doesn't move to the drop point. But its still quite a useful feature.
[Editor's note: I honestly can't recall if text could be dragged between Terminal windows in 10.1; can someone test and let us know? As a Cocoa app, I would think this has always worked, but I must admit I never tried dragging text OUT of the window, only IN.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020901084359832