The really cool use case in my mind is combining OLTP+OLAP in real time. Hence the interest in GPU acceleration. We have an OLTP platform that integrates a CPU version of the GAS engine used in MapGraph:

http://bigdata.com/bigdata

http://bigdata.com/mapgraph

Eventually we'd like to see the two platforms converge.

We are big fans of GraphLab. We used the version that was available when we collected the performance data on GraphLab - last summer. The asynchronous engine was seg-faulting which is why we used the synchronous engine. Lots of details about this in the SIGMOD paper:

http://mapgraph.io/papers/MapGraph-SIGMOD-2014.pdf

And of course MapGraph is open-source, so anyone can make their own comparisons. :-)