GridGain makes very simple, robust open source software for computational grids. It's ideal for performing parallelizable tasks, such as MapReduce (i.e, split the work, calculate, aggregate the results).
Check out technical info on the integration here, Nikita Ivanov's blog, and their integration page.
From an integration point-of-view what's interesting about this is that they used GigaSpaces' new OpenSpaces Framework (our open-source declarative API using Spring).
GridGain is the latest in our ongoing integration efforts with open source projects and cooperation with the companies behind them, including Mule ESB (MuleSource), Spring Framework (Interface21) and Hibernate.
Expect to hear more from us on this very soon.