The MapR team is sharp and responsive. It's founded by ex-Googlers from the search-infrastructure team (http://www.wired.com/wiredenterprise/2011/12/ex-google-man/).
M7 Tables are designed to be a drop in for HBase, with better performance and without the HBase complexity (it's much easier to run M7 Tables as the primary datastore for online apps).
M7 Tables support and certification for several key projects is coming along...
Spark 0.7 already works with MapR M7 Tables with the Hive images that were released with the Eco-1310 (http://doc.mapr.com/display/components/Hive+Release+Notes, http://answers.mapr.com/questions/7803/shark-spark-over-mfs).
MapR is in the process of certifying Titan (https://github.com/thinkaurelius/titan/wiki), and it's going is going through final QA right now (https://groups.google.com/d/msg/aureliusgraphs/RTeFVssIvoI/m...).