In real estate, everybody knows how important it is to be the first to pick up the phone. That good impression of the quick callback is simply an indication of service. So you wouldn't try to schedule a return phone call in one month, right?

People still schedule calls and meetings in half hour time slots a month in advance. In pre-Twitter days, perhaps scheduling a month in advance may have attached some kind of importance to the meeting, and implied that there was achievement on getting onto an A-lister's busy schedule.

Now, it's almost a sign of disrespect. As in "I can tweet with you, but are you kidding when you say we need to schedule our call or meeting on November 14?"

Warren Buffett is rumored to set up appointments 24 hours in advance. I'm busy, but my favorite mode of phone communication is simply finding out that somebody I need to speak with is online, and then prompting: "Hey, have 5 minutes?". This is efficient because everybody has some downtime throughout their day, and it's refreshing to have impromptu conversations. (I like Jon Washburn at Active Rain, who does that...)

In fact, try it on me... if I'm available, I'll take 5 minutes to talk with you.

Accessibility is service!