I've used Yahoo Pipes for some prototyping, but I'm unwilling reluctant to use it in full production as we'll have no control over it uptime etc.
Is there an (ideally open source) alternative that I can run on my own server? Or any application that can convert a pipe into PHP or Ruby?
What about this? http://pipes.deri.org/
"DERI Pipes: Open Source, Extendable, Embeddable Web Data Mashups
Inspired by Yahoo's Pipes, DERI Pipes is an engine and graphical environment for general Web Data transformations and Mashup. Supports RDF, XML, Microformats, JSON and binary streams. Use it as a "Web Pipe" or embedded in your applications Works as a mashup command Line tool Supports SPARQL, XQUERY, Several scripting languages. Extend it as needed DERI Pipes, in general, produce as an output streams of data (e.g. XML, RDF,JSON) that can be used by applications. However, when invoked by a normal browser, they provide a end user GUI for the user to enter parameter values and browse the results (see the examples below) ."