The newest jaw dropping viral discovery is a big one - literally. Philippe and colleagues describe 2 protozoan-infecting megaviruses (possibly part of a proposed group, the family Megaviridae, in the future?).
These guys are not tiny, simple or only subtly different. One virus, Pandoravirus salinus (from marine sediment at the mouth of Tunquen river, central Chile) was 1,000nm long (shaped like an amphora), 500nm wide, has a genome of 2,473,870-base pairs and potentially encodes 2,556 protein coding sequence (CDSs), 93% of which were novel. They do not seem to have a capsid, rather a trilayered tegument.
The second discovery was named P. dulcis and was found in the bottom of a freshwater pond near Melbourne in Australia; it's genome was 1,908,524-bp, encoding 1,502 CDSs.
Some more info at the Megavirus page.
Yeesh. The stuff we don't know...