In addition to security updates and a few other features, WordPress 3.4 (Grant Green) adds social functionality to your WordPress blog.
An example of this feature would be:[tweet http://twitter.com/couturefreak/status/217705414031187969]
And this is how Twitter Embed function works in your editor.
This is how you embed your tweets in the editor — just a link on it’s own line or a shortcode.
How-To Use WordPress Twitter Embeds
Either of these will work.
Obviously, the former one line link is easier.