Blogs of product management

http://leadonpurposeblog.com/

Magazine


http://www.onproductmanagement.net
http://productmanagementtips.com/
http://steveblank.com/
http://blog.sjohnson717.com/

insights blog


http://www.cindyalvarez.com/

And I also have a product blog at:

www.producttalk.org