I've been a 100% telecommuter for 7 years now and here's the important things I've learned:

1) Set a clearly defined schedule that works well with your team. I work with many people still in an office and I work a 9am-6pm schedule with 1 hour lunch at the same time they do so I'm always available when they are.
2) Dedicated office space. You need to have a work head space in addition to a home head space. The lack of decompression time in a commute and such is very noticeable, especially during crunch times at work.
3) Optimize your communication setup to be available to your team. My work relies a lot on IM, plus I've got a VOIP phone line, and I use Growl/Prowl to forward my instant messages to my phone when I'm working on a secondary machine, or otherwise not sitting at my main work machine.
4) Be proactive on communication: You'd be amazed at how much useful information gets conveyed in water cooler and casual conversation in an office that is actually relevant to work. You need to be very proactive in maintaining strong communication with your coworkers to stay in the loop and keep others in the loop.

Would be interesting to know how many of those telecommuters are the stay at home mom types selling Avon or running an online Etsy store as opposed to a full time employee clocking in a typical work week.

If everyone in the survey is a full time worker that's supposed to be doing a 40 hour work week then title should be changed to 'A Fifth of Telecommuters and their Managers Need to be Fired'.