• by Laurie Sullivan  @lauriesullivan, March 6, 2012

Cross-channel attribution that allows ad tracking from desktop computers to mobile devices is an ongoing challenge for online marketers and ad industry execs. Companies have figured out how to attribute clicks when it comes to tracking ads across similar hardware, but the model falls apart when attempting to follow users across devices.

Digital marketing provider IgnitionOne is working on tools to track attribution from PCs to smartphones to tablets, the company's CEO Will Margiloff told MediaPost. "We want to recognize the user across the three devices and attribute those various devices to the conversion similar to the way we track ads across the PC," he said.

Google, Microsoft and Yahoo have been working on the ability to traverse platforms, but it doesn't appear that the search engines will share the data with third-party companies. Microsoft supports Windows Live ID tying together the ability to track across devices.

Similarly, Yahoo is working on the ability to track Yahoo ID account holders, connecting searches on smartphones to tablets, desktops and laptops. The next move becomes the ability for advertisers to target ads across devices, according to Shashi Seth, senior vice president of search products at Yahoo.

Google said Monday it has begun to allow searchers to begin the search on a desktop and resume it on a mobile device when signed in to the search engine under the Recent icon. Information about previously searched places becomes available under an icon for about a day.

Third-party companies are on their own when it comes to tracking ads across devices. Industry insiders say they need the ability to drop in third-party cookies to track ads across devices.

Apple's devices now hold about 73% of tablet market share, according to Forrester Research. And iPad3 is expected to debut soon. Chatter suggests Apple on Wednesday will introduce a new TV iPadHD models that will impact engagement across multiple platforms, as company execs continue to try and sort through issues related to iAd tracking.