Payroll is the big thing stopping me from growing my team with work-from-homers. What if a member of the team is from another country? Do members submit their time each week, or are they all salaried? Trust is key in these situations too. Do you monitor code commits? Numbers of lines submitted each week? I worked from home when I was with IBM, and I always put in more hours than they paid me for. I would like to see more articles on how to make this work.
Trust is key no matter where they work. With a small company if you can't trust someone to be as productive as you need them to be (regardless of if you're looking over their shoulder or not) you probably shouldn't hire them. The exception to that I guess is people who just don't work well remotely. But the whole comment about monitoring code commits just seems nutty to me. My company is remote, and it works because I trust everyone to do a good job. I wouldn't hire someone I didn't trust.
That's where the expectations system comes in. Are they meeting their expectations? Then they're doing as much work as they're supposed to. Not meeting them? Then there's a problem, either with them or with the expectations.
If they're meeting expectations and you feel they're not working enough, then that's not their fault; it's the fault of the people setting expectations.