I believe you for sales roles, but this might not be the case in other roles. For example, in my slow-lane/day job I run a small team of Web site admins, content producers, etc. We all work from home. We all seem to do about 10 hours a day on average (sometimes peak at over 12 hours when something big is going on). We all love our work. We outperform comparable teams by about 50%. In fact the next nearest team (office based) were all laid off last year. Shame, but they were basically a work-shy water cooler discussion group.
Humm, having said all that, I am writing this in "work" time! I have better sign off now.