I am not, nor have I heard about this issue on any of the Evo sites.
First thing I would do is make sure that the battery is seated correctly in the phone itself.
Next I would put the charger in the wall and hook up the Mini USB to the phone and see if it starts a charge.
If not then wiggle the mini usb part that connects to your phone and see if its just not "tight enough" or something.
Then either way if you get to to connect for a few seconds you should take it to the nearest Sprint store and talk to them about getting it fixed.
If that does not work, then take it to sprint and get yourself a new one or see if they can figure out whats wrong.