Don't get me wrong, I'm all for telecommuting and did a 100% telecommuting gig for 3 years straight, but there's no way to get a days work done in 1 hour.
Headphones only go so far.
It's now 11:15. The developers start lunch at around 11:30 - noon every day, so there's no reason to get started on anything now. You get back from your hour lunch break at 12:45. There's a meeting on your outlook calendar at 1 o' clock, but you read the description and decide to skip it since there are already enough developers on the docket to give enough input. You're just gathering momentum at 1:05 when the Project Manager who organized the meeting appears at your desk, asking you to come to the meeting.
"I have a lot on my plate; the other two devs know enough about the system to keep the ball rolling."
"Well," she counters, "I really need everyone's input for this meeting." (Just like every other meeting.)
"There are 20 people on the invite list... if there are any problems, I'm sure I can just follow up with you after you send out the meeting minutes."
"Look, I really need you here for this; this isn't a skippable meeting." (None of hers are.) Finally you fold--you didn't take this job because you were a go-getter who knows how to tell people "no" repeatedly. The meeting is scheduled for 1PM - 2PM, but (like most meetings at this company), it goes until 2:30.
You get back to your desk and there are a dozen new IMs and e-mails blinking on your screen. You fantasize about just closing everything and working, but you've been here long enough to know that un-answered IMs and e-mails will result in people walking over to your desk, just like the jilted business user from this morning. For a couple of months you managed to put your foot down, mark yourself as "busy" in Outlook for the afternoon, and tell people that you simply won't deal with any non-critical problem during that period, but hearing complaints about issue turnaround time come through your boss was too much of a drain.
You answer IMs, follow up on e-mails, flip through high-priority code reviews and take care of other necessary busywork for about an hour and a half.
At 4PM, you get started on your work.
Note that of the distractions you describe, a lot of them are things that you would have still had if you were working from home. The emails and the IMs are still there, although I guess they might be more ignoreable since you don't have the threat of the person showing up at your desk. :-)
(Not that this is necessarily easy to do, or perfect, but I think we can accomplish more than we think in this manner.)
PS: And when you have 15 minutes to work it's next to impossible to figure out how to fix 392 without also creating 357 yet again.