I did brew upgrade, and brew update... then brew install steem and got
Error: No available formula with the name "steem"
==> Searching for similarly named formulae...
Error: No similarly named formulae found.
==> Searching taps...
Error: No formulae found in taps.
brew -v
Homebrew 0.9.9 (git revision 2b9a2; last commit 2016-07-21)
Homebrew/homebrew-core (git revision 51f94; last commit 2016-07-22)
So not sure why I am not getting the version 0.11 mentioned.
I went and found @teego's post here, and you need to install it directly from his repo. It's not part of "core" #Homebrew packages.
You can do that by running this command:
brew install TigerND/core/steem