Interim executives, like the temporary workforce, take assignments for limited terms and can help decrease a company’s expenses. But that’s pretty much where the comparison ends.

The specialty isn’t about filling slots temporarily — although interims can and do step in when a member of the executive suite steps down unexpectedly — but about bringing in highly experienced experts who come equipped to solve whatever challenging situation a company is experiencing.

In fact, think of it as exactly the opposite of seat-filling. It’s all about bringing dramatic results by expert hands under a tight deadline. Often, the situation is critical, like in the following example.

Motorola Mobility, the cellphone maker purchased by Google last May, recently announced a turnaround effort is underway. Interestingly, inside the company’s innovation wing, the demanding principles that guide the interim executive world are being put to use.

Interim executives are hired for the experience and judgment they bring to the table. In the topsy-turvy world of a turnaround or start-up, unique and perplexing scenarios inevitably arise. And interims, by definition, will likely face a wider variety of challenges over the course of time than their stay-put senior executive counterparts.

But, as the saying goes, it can be lonely at the top whether you’re a solo practitioner or even in a partnership.

Ernie Beal knows the pressure of being an interim CEO. With many states having vended out inmate health services to private enterprises, Ernie is running a new project for Corizon Health, a firm that operates clinics and hospital beds for inmates. One of Beal’s big challenges with this project is the need for tight security.

According to ManpowerGroup’s 2011 labor-shortage study, 52% of U.S employers surveyed said that a shortage of talent was keeping them from hiring more robustly.

“We know employers are struggling to fill open positions that require specialized and technical skills,” according to the staffing group’s survey. Management/executive positions made it into the study’s top-ten list of the hardest jobs for U.S. employers to fill.

Maybe those companies aren’t looking in the right places.

In business, everybody wants to be the cheetah: nimble, quick, flexible, and able to respond rapidly to twists and turns in the business cycle.

But even cheetahs band together when necessary, finding value in shared resources. The following story illustrates how well that can work.

Nick Clementi’s interim firm was created as a partnership of six executives who’d just gone through transactions as part of PE-owned ventures. They’d created liquidity events, he said, and found themselves sitting with cash but finished with their previous engagements.

What is an interim? Though the specialty of highly talented interim executives is quickly growing, many companies remain unaware of this critical resource. And despite Europe’s head-start in using interim executive labor, lack of clarity exists on both sides of the Atlantic as well as the rest of the globe.

Interim executives and consultants share traits. But consulting tends to be built around producing analysis and delivering a thought product. The definition of interim is different. An interim remains to get the grease on his or her hands as a company implements change. While analysis is a fundamental tool in the executive interim’s toolbox, the ability to implement and execute defines the interim. They can be essential during critical periods of a company’s life, including the stages of start-up, turnaround, or internal change.