Turn your iPhone into a mobile 3G modem!

US software firm and iPhone app developer NullRiver thought it was onto a good thing yesterday when it released its NetShare software onto Apple’s iPhone App Store.

The program was designed to overcome a major limitation of the iPhone: the inability to share its 3G Internet connection with a laptop by acting as an ad hoc or ‘tethered modem’.

This mode is a standard inclusion on most serious smartphones including the BlackBerry Bold and is popular with mobile professionals and power users who want to briefly tap into a full Internet experience on their notebook when there’s no Wi-Fi within reach.

NetShare didn’t even do that much alas – it was limited to running Apple’s Safari desktop browser by turning the iPhone into a SOCKS5 proxy server. Yet NullRiver fell foul of Apple which allegedly chose not to implement a ‘tethered mode’ on the iPhone 3G to appease US carrier and premium iPhone partner AT&T. The telco considers tethering as a cost-extra service for which it charges customers US$30 per month.

NetShare had been online for only a few hours – enough for word to spread like wildfire in the iPhone community – when the application was mysteriously removed from the iPhone App Store. Later in the day NetShare reappeared and vanished once more before surfacing overnight.

NullRiver says it has received no warning or explanation from Apple during this brief and puzzling brush with the company’s heavy hand. “We’re not quite sure why Apple took down the NetShare application yet we’ve received no communication from Apple thus far” according to a post on the company’s Web site. “NetShare did not violate any of the Developer or AppStore agreements.”

Unfortunately the program remains unavailable to Australian customers: clicking on an iPhone App Store link sourced from a US-based iTunes account returns the message that  “the item you’ve requested is currently not available in the Australian store”.

And there’s no other way to get the program: iPhone programs can be downloaded and installed only via Apple’s online store while commercial offerings like NetShare (which sells for US$9.99) are protected from copying by the same FairPlay DRM shield as music purchased through iTunes.

We’re hopeful NetShare will pop up locally as it provides a simple solution for the mobile digerati – and would be especially effective when partnered with one of Virgin’s super-generous iPhone plans which serve up 1GB of data on a $70 cap or 5GB for $100. Tutorials tweaks and add-ons which extend NetShare’s capabilities to other browsers and applications have already started to appear.