Hi, adsense has a new ad unit size 300x600
It can replace two 300x250 ad units that you have one above the other in your sidebar or within your content (with div float)
So you replace the two 300x250 ad units by this one, and you can then put another ad unit on your page somewhere else.
At the moment this new size mainly displays lots of text ads, but there are also a few graphic ads using this size and for sure the advertizers will be jumping on this new format.
Have you already implemented this new ad unit? What are the results?