Update: the article I linked to below is very useful. It shows me how to do something that I’ve long wanted to learn how to do, namely sync calendars and tasks across applications. Basically it includes using Google sync.

In his classic book Getting Things Done (GTD to the cognoscenti), Dave Allen points out how your brain is kinda stupid. He means the human brain in general, not yours specifically of course, and he gives this example of how, if your brain were really smart, it would remind you to get new batteries for your torch when you were passing the battery section in the store (and also remind you what size batteries you need) instead of “reminding” you that you need new batteries when you try the torch and it doesn’t work.

His GTD system is designed to get as close to that ideal as possible: you create lists of things to do based on context, like @work, @office, @out, @computer, @train, etc. Then, when you’re on the train or out running errands you open the list of “things to do” for that context.

Well, Apple’s iOS 5 apparently has an app that will ping you a reminder, not just based on a calendar entry, but also on location! Check this out (note the date – this is not new news, except to out-of-date fogeys like me):

June 2011 Update: Apple recently announced the transition to iOS 5, which has several features that make the Touch and even better PDA. Of course, it is far more than a PDA, but this post focuses on its PDA features.

The new features include a Reminder app, the ability to use Text Shortcuts, a Mail app that supports rich text, an improved Calendar app ability to show colors for different types of appointments, for example, WiFi syncing, and a notification center that shows all of your notifications in one spot.

… Note that the Reminder app is location-based, so you can set a reminder to go off when you enter your grocery store. Just add the store and its address to your Contacts, and then you can select its location for an errand, if you choose.

via Apple’s iPod Touch is a Great PDA, Not Just an Entertainer.