Actually Doug Cutting himself (who created Hadoop) tweeted about this. I guess Spark gets some of his blessing :)

As pointed out in the article multiple times, we are comparing with MR here. We are not comparing with Hadoop as an ecosystem. Spark plays nicely with Hadoop. As a matter of fact, this experiment ran on HDFS.

In terms of vibrant community, Spark is now the largest open source Big Data project by community/contributor count. More than 300 people have contributed code to the project.