A new report from mobile ad network AdMob Inc. claims that worldwide iPhone ad requests grew 52 percent month over month to 359 million in November, giving the Apple smartphone 6.3 percent share of total requests globally.

The iPhone is now the No. 1 device with 9.9 percent of requests nationwide, according to the November AdMob Mobile Metrics Report circulated to clients. Another key finding in the report was the rapid growth of Wi-Fi in the United States and Britain.

"Wi-Fi usage in the U.S. and U.K. has started to explode and we think that's going to be a fascinating trend to watch next year," said Nicole Leverich, director of corporate communications at AdMob, San Mateo, CA.

"It's really being driven by the new smartphones on the market -- the iPhone, the G1 and the BlackBerry Bold," she said.

Per the report, the iPhone has the most Wi-Fi usage, with 42 percent of the requests nationwide coming in over Wi-Fi and not a wireless carrier's network. The comparable data for other smartphones is between 10 percent and 20 percent nationwide.

But there is increasing traffic from non-phone mobile devices as well.

"The fact that we're seeing mobile traffic from mobile devices that aren't phones like the iPod touch and Sony PlayStation Portable opens up a new area of opportunity for mobile marketers," Ms. Leverich said.

The AdMob metrics report had other findings as well.

For example, 8 percent of total requests nationwide in November were on Wi-Fi networks, up 3 percent from August. It was the same picture in Britain, except that it was up 4 percent from August.

In Britain, the Nokia N95 and other Nseries phones are the leading Wi-Fi devices after the iPhone and iPod touch.

However, worldwide ad requests, at 5.8 billion, were flat from October to November.

While requests from North America, Western Europe, Latin America and Eastern Europe were up 10 percent month over month, that was offset by a decline in Indonesian inventory.

"There were changes in AdMob's publisher mix in Indonesia that accounted for that decline," Ms. Leverich. "We don't think this is representative of a decline in mobile Web usage in the region."

Meanwhile, the Android-backed G1 HTC Dream phone generated 15 million ad requests in November, accounting for 7 percent of all T-Mobile traffic.

Android, a mobile operating system from Google and its partners, has a 2 percent share of smartphone operating system traffic nationwide, according to AdMob.

AdMob stores and analyzes handset and carrier data from each ad request in its network to optimize ad serving. The company aggregates this data monthly to offer a peek into mobile trends.

"This report shows that mobile advertising continues to grow and new opportunities like Wi-Fi are emerging," Ms. Leverich said.