Mobile advertising platform/exchange Velti announced this morning that it closed a two-year $27 million US mobile marketing deal. The client company was unnamed in the announcement; however Velti characterized it as "a major US brand." Velti also described the deal as the "largest ever mobile marketing deal."

Velti said that the focus of the mystery marketer's mobile efforts would be engagement and loyalty: "This program will drive increased engagement with and long-term loyalty of the brands existing customers." It will be interesting to see what sort of "mobile marketing" is involved and how much "advertising" or mobile media buying is actually part of this deal.

Velti's Q2 global revenues were $58.7 million. The US market is generating a majority of Velti's revenues and this deal would make the mystery company one of Velti's largest clients. Indeed, the announcement was aimed primarily at financial markets. And Velti got a roughly 10% "pop" as a result. 

Mobile CPMs are mostly lower than desktop CPM rates (Facebook is one of several exceptions), although they were much higher a few years ago. The chart above shows "eCPM" figures received by publishers by content category. Education leads with$0.97, up from $0.82 in July. 

Notwithstanding the huge deal announced by Velti, most marketers are still undervaluing mobile today. There's also an oversupply of mobile display inventory: more ad impressions than advertiser demand currently.