One a feature plugin feels ready for merge, the developers of the plugin submit a merge proposal for the core team. The oEmbed API plugin — which I gave an overview of last week — has reached that stage:
For the past 6 years, users have been able to embed YouTube videos, tweets and many other resources on their sites through a nifty feature called oEmbed.
Today, we (mainly me, @pento and @melchoyce) ask to consider extending this feature by merging the oEmbed API plugin into WordPress core. This plugin allows anyone to embed posts from your site by just pasting its URL. We’ve been working hard on it for months and are now eager to hear your feedback.
The plugin is working well, is flexible, and the team thinks its ready for merge. This is one of those features that not everyone will use, but it's a feature best suited when all installs support it. So if it's included, it makes much more sense at a core level than to remain as a plugin forever.
If you haven't tested it now is definitely a good time to do so. See the merge proposal for full info.