Google announces it will soon be available for AdSense ad units 300 × 600 pixels, also called unit half page.

The format 300 x 600 format is one of the fastest growing per-impression and is indicative of a trend where publishers offer ad formats with visually more attractive and, therefore, preferred by advertisers promoting a brand. Since this ad unit is new to our network, currently in these placements will see a large number of text ads.