A containment result in complexity
Aaronson's result shows that $\Pi_2 \not\subset P^{N\!P}$ relative to a random oracle with probability 1. As he mentions, it had already been known that $N\! P != \mathrm{co}N\! P$ (and so $P \neq N\!P$ and $P \neq \mathrm{co}N\!P$) relative to a random oracle with probability 1: see the paper by Bennett and Gill. An oracle with respect to which $P \neq N\!P$ (and so $P \neq \mathrm{co}N\!P$) had been constructed earlier by Baker, Gill and Solovay. The construction is standard, and you can find many references online.