We've been here before but Google seems to be blocking Yahoo Pipes again.
Here's the catch. I think Google likes Yahoo Pipes. Google's even demonstrated how Yahoo Pipes can be used. When I pointed out that Feedburner was blocking Pipes I even had MC pop over to the blog to make sure everything was okay.
So I don't think Google intends to block Yahoo Pipes. I think Google constantly fights off RSS scrapers and sometimes Yahoo Pipes gets caught in the crossfire. The screen grab above shows how it's the blogsearch results that are being blocked.