Apple this week stepped up its efforts to take on rivals Research in Motion and Microsoft in the corporate smartphone market, releasing a lengthy guide aimed at helping system administrators deploy iPhones throughout big businesses while simultaneously taking advantage of over a dozen new enterprise features delivered this week.

The 83-page guide, titled “iPhone OS Enterprise Deployment Guide: First Edition, for Version 3.0 or later,” highlights 18 new corporate-friendly features in iPhone Software 3.0, signaling the Cupertino-based company’s most recent efforts yet to push adoption of its touchscreen handset in a market currently dominated by devices running variants of Windows Mobile or BlackBerry operating systems.

Guide is here in PDF Form: http://manuals.info.apple.com/en_US/Enterprise_Deployment_Guide.pdf

If Apple intends to gain a dominant share of the enterprise market, the company has its work cut out for it. A study released by TradingMarkets in April of this year shows that BlackBerry and Windows Mobile hold a combined 63 percent total market share. The same report also states that Apple’s iPhone – along with Google Android and Symbian devices – “are not serious contenders for U.S. business use.” Clearly that’s a stigma Apple hopes to change.

For businesses to make the leap to the iPhone may not be too difficult a transition: the report highlights AT&T, the iPhone’s exclusive U.S. provider, as a dominant enterprise carrier, along with Verizon.

The enterprise smartphone market has been in Apple’s sights for the duration of the iPhone’s existence, but the company has pushed harder to compete in the space with each update to the phone’s software. In 2008, chief executive Steve Jobs introduced initiatives to appeal to business users. More than a year later, that plan is still being carried out with this week’s launch of the version 3.0 operating system.

Apple has also maintained an enterprise-centric section on its Web site to promote its phone in the corporate world, in which it bills the handset as “The best phone for business. Ever.” Here’s that section: http://www.apple.com/iphone/enterprise/