Every once in awhile you see one API provider making use of APIs from another. This is the case with the eBay Developers Program, who have announced the new eBay API Release Calendar. The calendar is itself a mashup, having been developed using the Google Calendar API. The resulting app is simple but works well: it's color-coded to distinguish the significance of dates that correspond to each event.
As Laurel Kline noted in the announcement:
In the Month view, you get an overview of everything released or enforced that month. Click the Agenda tab and you can use it as a checklist for adopting upcoming features. Click the event and a detail balloon pops up. You can also copy that event to your own calendar. Since it's powered by Google Calendar, you can subscribe to it just like any other public calendar. Subscribe just to the High Impact calendar, or subscribe to all of them.
As with this mashup, the Google Calendar API enables the development of client applications for updating and viewing customized online calendars. The API also provides event search capabilities. For more, see our Google Calendar API profile and our list of 29 example mashups. And our API directory includes a variety of eBay APIs.