This is implemented by the Locale Play Sound Plug-in on the Android Market. There are two different plug-ins by different developers. One can play any sound while the other has a fixed set of sounds.

It turns out that Google introduced a subtle, nasty, undocumented change in Android 1.6/2.0 that could cause apps to fail when determining location with GPS. This issue has been worked around in Locale 0.694.

Note that GPS requires a clear view of the sky, and does not work indoors. If Locale cannot quickly get a position from GPS, it may choose to abort rather than keep searching in an effort to conserve battery life.

This is now supported in Locale 1.0. To add multiple conditions of the same type, simply long-press on the Add Condition button.

Locale 1.0 is available on the Android Market today in countries that support paid apps. Full release notes are here: http://www.twofortyfouram.com/notes.html

At long last Locale 3.0 introduces the Calendar condition to detect events on your Google Calendar, Exchange Calendar, or any other calendar supported by Android.

While Locale 3.0 is available for Android 2.2 or later, the Calendar condition requires Android 4.0 or later. To learn more about Locale 3.0, please see our release notes here http://blog.twofortyfouram.com/post/19303488607/locale-3-0