Roberto Masiero vividly remembers the moment in 2011 when it became clear to him that designing a mobile application was a considerably different effort than designing a desktop application.

As head of the innovation labs for ADP, the $10 billion payroll services firm, he managed the engineering team tasked with creating ADP Mobile, the company's version of its human capital management application for mobile devices.

"We started out with a list of 100 features that we thought were awesome," Masiero remembers, but his team's enthusiasm ran smack into the collective disdain of the user experience designers they'd brought in from an outside agency, who deemed feature after feature irrelevant for mobile users, arguing that so many options would just confuse them.

By the time the designers were done, they had whittled the list of features down by 80%. "Their message was simple," says Masiero. "Less is more." In a mobile application, it is better to cleanly provide the 20 most important pieces of information than force people to navigate through 100 that they might never use. "We learned that you have to drop completeness in the name of usefulness."

What's more, Masiero, like a lot of other tech leaders, realized that in this age of mobility and user-driven technology, IT shops that don't have a user experience expert onboard need to get serious about begging, borrowing or stealing one -- an increasingly difficult proposition.

Developers with user interface (UI) and user experience (UX) expertise are hot these days, according to Shane Bernstein, managing director of QConnects, a Culver City, Calif.-based digital recruitment firm. And it's a fairly recent phenomenon, he says. Between 2010 and 2011, QConnects saw a 25% increase in the number of requests for UX designers; between 2011 and 2012, the increase was 70%.

Salaries are going up as well. Recruiters cite starting salaries ranging from $70,000 to $110,000, with the upper end hitting $150,000 and up. The Creative Group, a division of Robert Half Technology that specializes in design, marketing and interactive talent, began tracking UX designers separately in its annual salary survey in 2011. Salaries went up 6.2% in 2012 and it expects another 4.8% increase in 2013.

"And be prepared for a local variance factor," says Donna Farrugia, executive director of The Creative Group. "If you live between San Francisco and San Jose, add 30%."

Thanks to Apple, users expect perfection

In design parlance, the user interface (UI) is what the user sees; the user experience (UX) is how the application behaves. Both recruiters and practitioners stress that designers need to know the latter as much as the former. That is, they need to concentrate not only on how a design looks, but on the whole "wireframe" of the application, and where their requests are going into the back-end of the system.

What's driving the demand for such skills? Many people in the industry lay the credit -- or perhaps blame -- on Apple, with its near-fetishistic attention to how design, hardware and interface intersect. "Now people expect everything they interface with to have the ease of use of the iPhone," says Matt Miller, CTO of Irvine, Calif.-based technical recruiting firm CyberCoders.