I've just found a blog (screenshot, just in case), used by one of Google's trusted testers*, that describes one of the tests.
1. Log in to writely-testing
2. Open a new presentation
3. Insert text above the slide title
4. Observe the text above the slide title is displayed below in view presentation
The post is very recent (March 13) and gives another clue that Presently will be a part of Writely (now known as Google Docs).
* Here are some snippets from his/her posts. Most of the posts have been removed.