Japan's No. 2 carrier, KDDI, today said it plans to offer a new mobile e-mail service powered by Google's Gmail. This is the latest in a long line of Google-related mobile announcements. While Google's mobile onslaught continues, this question remains: Just how successful are the search giant's efforts?

In recent weeks Google dominated headlines with its plans to participate in the upcoming FCC spectrum auction and with its partnership with Sprint to offer Web services over WiMax. The iPhone may be the No. 1 mobile story of 2007, but Google is a close second.

Despite the fact that Google is pushing mobile, this space is challenging. As I blogged a few weeks ago, Google's mobile initiatives have proven difficult. Sure, Google is the No. 1 mobile Web site, but we don't know how many people are using Google's other mobile services, like Gmail. We also have no idea if Google's mobile efforts have turned a profit, and if not, if they will in the near term.

Google has said repeatedly that mobile is the future. But how long will Google -- and the rest of the Web -- have to wait on that future?

What do you think? When will Google's mobile efforts show fruit? Is Google really more successful in the mobile market than analysts are giving it credit for?