That where recently brought to my attention.
I got this from Oren Dobzinski:
Cassovary - new graph processing library from Twitter. Pankaj Gupta from Twitter is involved in this project. Since he is also a program committee member of our GraphLab workshop it will be very interesting to learn about this new system.
Ted Willke from Intel Labs brought to my attention the following project:
Galois - executes serial c++ code in parallel on multicore machines.
Mika Illouz from Eigendog recommended on the following projects:
julia a new programming language, aims to be R/Matlab for clusters.
Definitely a lot of activity in this domain.