There is a plugin for this:
http://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Import-Export/Adobe_After_Effects
Setup
To enable it you can use the user preferences File>User Preferences (CtrlAltU)
Go to the addons tab
Search for "After Effects" if the plugin pops up, enable it.
If nothing comes up, download the addon, and install it using these steps:
https://blender.stackexchange.com/a/1689/3127
Usage
Select the objects and camera etc that you wish to export, and go to File>Export>Adobe After Effect (.jsx)
Save the file.
Open After Effects (Version > CS2)
File>Scripts>Run Script File and select your file. It will ask you to name the comp. Any name will work
Next, after it is done, go into the Project panel and open up your comp. A bunch of nulls and a camera should be there, matching the motion of the ones in blender.