I've been playing around a little bit with Yahoo! Pipes. I won't write too much about it, since a lot of people already have. There are some interesting things about it, both from a technical perspective, and from a "wow, neato" perspective.
<accent type="Boston">The UI is wicked cool.</accent>
A few years ago (2? 3?) we talked about putting a "Visio-like" UI on our new product at work. That got nixed in favor of something a little more understandable for the average system administrator. The Pipes UI is fairly simple, but still probably over the head of the average, non-technical person. It's not without bugs and is missing some operators, but in general it works pretty well.
Being able to take RSS sources and munge them is something that will make mashups and such a ton easier. There are tons of pipes that people have built including aggregating news from multiple sources on a given topic or day, viewing the news through Flickr, etc.
For my first pipe, I redid how I post links to my site. I setup a pipe that takes my links from del.icio.us, finds a picture from Flickr that fits one of them (based on tags, comments, title, etc.) and passes that back to me. I rewrote my python script to grab that data and put one picture at the top of my links. Hopefully this will all work--we'll see the next time I link stuff.
