preg match @ sign

[eluser]new_igniter[/eluser]
I am new to preg match but hoping someone could help me write a reg ex that would do something like the following:
I want to parse twitter feeds and pull out the content when someone posts "at" someone. This always begins with the @ sign then the name, and then the content.

How do I write something like "look for the at sign, then copy everything until there is a space after the name.

I am using get file contents, so the actual html looks like this
@<a href="/ev">ev</a>