Managers really shouldn't have to do anything very different when doing appraisals for telecommuters. The appraisal should focus on the results that were expected and achieved. What counts is the product, or the deliverable - not the number of hours the person spent in the office.

Sometimes, managers of telecommuters might find that their telecommuters have discovered new, more efficient ways to get the job done. If that's the case, be sure you don't penalize your telecommuters for being creative - as long as they are still able to deliver what you expect from them.