As mentioned on the Zend Developer Zone and by John Herren, Yahoo! has added a new feature to its Pipes functionality - serialized PHP results.

Until now JSON output has been the only way to obtain all the data flowing through a Pipe. Starting today we've added a second way of getting all the data - serialized PHP Pipe output. [...] It's then up to you on how you want to display or use the Pipe data. The possibilities are endless.

If you haven't messed with Yahoo's Pipes system, you owe to it to yourself to at least go and play with it for a little bit.