How many ad networks can mobile support? Are we heading for a shake-in/shake-out? And, if so, what capabilities will likely separate the winners from the also-rans? These are just some of the key questions that came up during interviews with ad network executives at Mobile World Congress (MWC), and in a string of recent phone briefings. It's also a line of questioning I hope to pursue at ThinkMobile, and Meet the Mobile Ad Networks, a panel led by Steve Smith with guest speakers Steven Rosenblatt, VP of Advertising Sales, Quattro Wireless; Eric Eller, Senior Vice President, Client Solutions, Millennial Media; Patricia Clark, Regional VP of Sales, 4INFO; Paran Johar, CMO, JumpTap; Brian Murphy, Eastern Regional Sales Director, AdMob; and Robert Walczak, CEO & Founder, Ringleader Digital. It's going to be a great session, and I'll be back with my observations after the event. BTW: Steve is a must-read columnist at MediaPost. Yesterday's post, which recounts an experiment (a random click through mobile ads) and the user experience (disappointing and even frustrating), should be mandatory reading at ad agencies and networks everywhere. A key takeaway: "The system still is clogged with some crap even at branded media sites. Of course there are still dancing mortgage celebrants on CNN's homepage, so we can't fault mobile too much. But clicking on a mobile ad is an iffy thing. Mobile users don't know yet what to expect, so if the publishing brand can ensure quality advertisers with quality end-user experiences, it elevates both the ads and the content." Steve's column and my own observations lead me back to the key questions: How do the dedicated mobile ad networks fit in the game, and how will they differentiate? I caught up with Zaw Thet, CEO of 4INFO, the 800-pound gorilla of mobile messaging, and the company that Nielsen identified as the largest SMS content provider in North America for 4Q2008, to get the inside track on AdHaven (a new product 4INFO launched just prior to MWC that represents a rebranding of its entire suite of ad serving products) and where it fits into the roadmap.