I have seen this technique a few times now, and am not sure what it is called, so not sure how to search for it. As the shot finishes, the barista takes a small spoon and sticks it under the spout of the portafilter for just a second, and quickly dumps the contents into the drip tray. Here are two examples of this motion:

http://www.youtube.com/watch?v=xVYmcVgfDNA (at 1:06 - I tried to paste a timestamped link, but it gets truncated)



I am just curious what the purpose of this motion is, and I figured someone here would know for sure! My guess is that it is to prevent the last drops of espresso from landing on the rim of the cup as it is removed, but that is just a guess (and if correct, is a problem I have never thought to solve as a home barista). Any experts know what this motion accomplishes? Thank you!

Your guess is correct. And in the first video at the Italian cafe, the barista is just doing it with a bit more flair.