Honestly, I am not sure if this is brand new, but a DigitalPoint Forums thread reports the Large Rectangle (336 x 280) unit as having four text ads within it as new.
Here is a screen capture of the ad unit:
A typical ad unit looks like what you see listed on the Google AdSense ad formats page. I.e. four lines of ads and not four boxes of ads. Here is a live ad from my AdSense account for testing purposes:
Forum discussion at DigitalPoint Forums.