Here is a list of resources to keep you up to date with mobile marketing
A great place to see whats happening in the mobile marketing world is the mobile marketing magazine.
Their sister magazine Mobile retailing is also good for ideas and resources.
QR Codes reviews and strategies
10 Ways to use CSS tables in your Mobile design
Another Mobile Marketing Magazine
Mobile Marketer magazine blog
Linkedin mobile marketing and advertising
A great place to find out whats happening in the mobile arena
A great video from a Google conference on the future of mobile marketing.
Found some great resources list them below in the comments.