I met the Nimbula guys a few years ago and I was quite impressed.
What hasn't been impressive is Oracle's cloud efforts. Well one way to solve this problem for Oracle is to buy Nimbula.
An interesting observation by Derrick Harris is the difficulty of selling the private cloud.
Nimbula was on the scene early and, from all accounts, built a good product, but appears to have succumbed to a lackluster private-cloud buying market. It has a handful of publicly named customers, including Russian search engine giant Yandex, but like so many other private-cloud startups, it might have fallen victim to market confusion (i.e., “Can’t we just keep buying VMware?”) and an industry consensus around OpenStack as the private-cloud savior. Indeed, last year, Nimbula made a strong pivot and actually began rebuilding itself as an OpenStack distribution.