Forrester has started a Product Management blog. There is already some content out there but I suggest you subscribe to it.
http://blogs.forrester.com/product_management/
Also, their latest entry is regarding product management surveys and they are looking for participants.
Thanks for the mention!
By the way, we're running two surveys about product management. If you want to contribute, here are the links:
Product management tasks and responsibilities
http://deploy.ztelligence.com/start/index.jsp?PIN=139WSYDWFN2GJ
Tools for product managers
http://deploy.ztelligence.com/start/index.jsp?PIN=139WBA3H7EYQZ
Each takes about 15-20 minutes to complete.