Calendar shows yesterday

I don't really care about "automatically revert to the current day after a period of time" during the course of the day, but I've noticed the same "sleep laptop at night, wake up in morning" phenomena.

Try this:
1) Set the view in Today to be yesterday.
2) Quit Today and relaunch.

The view is reset to today. The problem is I rarely quit anything, I sleep my Mac instead. :)

It's not a big deal to me to click the Today bar to reset the data view but it would be sort of nice if Today changed automatically when the current date changes like it does on launch.

I mentioned the "automatically revert after a period of time" approach because I think it would be bad form if I had set the view to a certain future day for reference, then closed Today for just a couple of minutes, then opened it again ... only to find that it had been reset. I agree with Justin's sentiments in that case.

If I opened it again 3 hours later or the next day, though, I would expect it to have reset to "what's going on now." The appropriate amount of time that must pass before reverting would certainly be subjective. Maybe 30 minutes would be appropriate, or maybe it could be user configurable to accommodate personal preference.

"Maybe 30 minutes would be appropriate, or maybe it could be user configurable to accommodate personal preference."

The problem with configuring it as a preference is that the more preferences there are the more complicated things get. Additionally, a lot of users don't poke around much in preferences and simply accept the default, so I believe it's important to get the default behavior correct.

The only time I have this issue is first thing in the morning because the date has switched. Even then it's not that big a deal to me.

If I used the date browser to poke around in other days, I almost always click the Today bar to reset the view to today when I'm finished.

Since the Today bar checks every minute for the current date, it seems to me that when it detects a new date and changes the Today bar, it could also reset the view at that time. That would solve what I suspect is the most common problem without adding a preference. I really don't think users returning to Today after 30 minutes or 3 hours would be as bothered to see the "wrong day" when they explicitly changed it earlier in the day.

I find it odd as a quick reference tool that Today often shows yesterday's view when my computer is left on 'across midnight'.

I'm no programmer but what you if put something in that checks the Today display date at midnight then switches over to the present day's info. THEN make that process an toggleable option.

I'm not sure of all the usage cases you are trying to appease but this would work for the people that always want it current and the people that want it to update only when they click on the date inside Today (assuming the concept is doable from a programing POV).

How I feel is yesterday is gone "Today" is Today.
I clicked on it and expect to see Today's appointments.

You could make it by default like that and a check box that says "Always show Today by Default"