I am working on adding In-App purchases to my app.
I am able to receive the productsRequest:didReceiveResponse
method, and receive the array of products
I assume you've done the standard sanity checks: double-checking your code, confirming your product IDs, comparing your code to the In-App Purchase Programming Guide, etc.
This may be ridiculous, but -- if you're certain your code is correct -- do a hard reset (full wipe) of your iPod (Settings => General => Reset => Erase All Content and Settings). I puzzled over this exact problem for hours -- it turned out my code was correct and the hard reset was the solution.