While playing around in the APEX 5 EA2 environment I discovered a few neat little features for Calendar regions.
First of all you can export the data of the calendar - only the data that's currently visible - to four types of format. Especially the iCal format is new and interesting as this is readable by most calendar applications. Right now, in EA2, the PDF option doesn't seem to work yet. And alas, the iCal format is not readable by the Apple Calendar - but I hope that'll be fixed when the product becomes available! It is promising nevertheless....
Another cool feature is the Google URL. You can enter a URL of a public Gcalendar (or your private calendar if you want to) and your appointments will show up in your APEX application (see the green entries in the screenshot below)!
And last but not least : You can add your own (or someone else's) RESTful webservice feed to the calendar as well. By defining your own Resource Handler using a query to return a JSON string, you can add even more data sources to your calendar. The purple entry below is created by the SQL statement:
select 'Presentation APEX5 Hidden Features' as "title"
, sysdate - 0.5/24 as "start"
, sysdate + 0.5/24 as "end"
The JSON format is fixed, so we have to embed the columns in quotes to get a proper SQL statement (otherwise we are using reserved words and return uppercase attribute names).