In our company, we've been using Yahoo Pipes for quite a long time and we're still using it for some specific and more complex feeds.
Otherwise, we are developing a simple Sinatra-based application to work like Yahoo Pipes and return the result as a standardized XML/JSON response.
It's quite simple to create such application, however I agree with Pascal. Between Yahoo's servers and yours, relying on Yahoo! should be more effective than relying on a custom server.
The only Pipes downside we've been experiencing is the API throttle. We've partially solved the issue caching the responses on our side and implementing a custom throttling mechanism to dynamically slow down requests when Pipes returns an HTTP error.
