The first update for WordPress 3.8 is now out – WordPress 3.8.1 was released yesterday and if your site supports it, the background update will take place automatically for you. Otherwise simply venture in to your dashboard and click the update link and follow the standard procedure.
Here’s what the Make Core team’s official announcement had to say about version 3.8.1
Version 3.8.1 is a maintenance releases that addresses 31 bugs in 3.8, including various fixes and improvements for the new dashboard design and new themes admin screen. An issue with taxonomy queries in WP_Query was resolved. And if you’ve been frustrated by submit buttons that won’t do anything when you click on them (or thought you were going crazy, like some of us), we’ve found and fixed this “dead zone” on submit buttons.
It also contains a fix for embedding tweets (by placing the URL to the tweet on its own line), which was broken due to a recent Twitter API change. (For more on Embeds, see the Codex.)
I would like to encourage you all to check the Fourteen Extended settings and report any issues if any so that I can get them addressed as soon as possible.