During my interview with AT&T (T) CEO Randall Stephenson at Fortune’s Brainstorm TECH conference, he said he was in possession of something that was the envy of his one-time boss, TelMex’s (TII) Carlos Slim Helu: an iPhone app.

Okay, it isn’t just any old app for Apple’s (AAPL) phone. Stephenson’s tech folks helped build him a special application that tracks the companies in AT&T’s “ecosystem” – partners, competitors, etc. The digital list was inspired, in part, from a paper map that Slim carries around with the names and financial metrics of companies in his universe.

Apparently at a recent meeting, Slim (who is one of the richest men in the world) pulled out his paper, and Stephenson noted that some of the information was out of date. Stephenson pulled out his iPhone and provided some of the updated information from his app. According to Stephenson, Slim (a former technophobe who apparently has become an active BlackBerry user) was definitely desirous of Stephenson’s technology.

Possible opportunity for BlackBerry app developers? As Stephenson pointed out on the panel, Slim does have a dollar or two to spare.