This has existed for years now... I don't understand what's there to develop, really.Quote from Daal:
"CME Group is developing a new "FedWatch" tool that will allow you to quickly calculate the market's expectations of actions by the Fed at future FOMC meetings, based on Fed Funds futures daily settlement prices. Watch for more information on the availability of this tool soon."
Check this out here (based on FedFund futures options prices):
http://www.clevelandfed.org/research/data/fedfunds/index.cfm
BBG has the FFIP fuctionality, which allows you to imply the probabilities using either options or futures prices. It's also quite easy to create your own spreadsheet in Excel, but would very much depend on how sophisticated you wanna get. The Cleveland Fed methodology is quite rigorous and accurate.