The latest iPhone software has led to surge in Wi-Fi connections, according to data from AT&T.

The second largest U.S. wireless carrier said nearly 15 million users connected to their public wireless hotspots last quarter, which is a 41% increase from the previous quarter. One of the major reasons for this is that the iPhone 3.0 software makes it easier for users to log on to AT&T's Wi-Fi at places such as Starbucks, McDonald's, and other public locations.

Prior to the 3.0 software, logging in was considered tedious. Users had to enter a phone number, receive an SMS message, and then click a link in that text message to access the Wi-Fi. The latest firmware automatically detects and logs in iPhone users without the two-step authentication process.

"Our Wi-Fi network is a competitive differentiator for AT&T and a major value for our customers," said David Christopher, AT&T's chief marketing officer, in a statement. "It's another reason that twice as many smartphone customers choose AT&T than any other carrier."

AT&T offers iPhone and BlackBerry users free Wi-Fi at certain public venues, and it is seeing increased interest in this. The company said it has already had 25.6 million Wi-Fi connections for 2009, which already surpasses the 20 million times the service was used in all of 2008. The service also has the added benefit of easing demand on AT&T's 3G network, which many iPhone users have complained about.

AT&T rivals are also using Wi-Fi as a value-add for subscribers, as multiple T-Mobile smartphones can use Wi-Fi as part of the company's HotSpot@Home home-calling service. Verizon is giving its FiOS customers free Wi-Fi access at more than 100,000 hotspots around the world, and Sprint Nextel is requiring its future BlackBerry smartphones to sport Wi-Fi chips.

The iPhone may be your next full-function computer. InformationWeek has published an independent analysis of this topic. Download the report here (registration required).