eBooks & Devices
The W3C Mobility can run tests on a web page to determine its "mobile-friendliness." Be sure to also check out the W3C's recommendations for best practices: www.w3.org/TR/mobileOK-basic10-tests/
The Library Success: A Best Practices Wiki is "a one-stop shop for great ideas and information for all types of librarians." Included on this wiki is a page on M-Libraries with many examples from these categories: Libraries offering mobile interfaces or applications, Vendors and Publishers, Possible Health Effects, and Suggested Reading. The Wiki also has resources pages on IM and SMS reference services.
The users_Lib group on Flickr has several sets with mobile interfaces images.