When I added Amazon.com to our SaaS 20 Stock Index, a few readers asked me whether the online retailer is really a software as a service (SaaS) company. My answer: Absolutely. And a growing number of tech companies agree with me.

A prime example: Red Hat has inked a SaaS partnership with Amazon.com to offer JBoss middleware as a hosted service. Here’s a look at the deal, and its implications for managed service providers.

At Red Hat Summit in Boston, the open source company disclosed that JBoss Enterprise Application Platform is now available within the Amazon Elastic Compute Cloud (Amazon EC2). Red Hat claims JBoss is the first cloud-based application server.

For MSPs, the Red Hat-Amazon relationship is the latest example of open source software moving into the cloud. Red Hat Enterprise Linux was already available through Amazon EC2. And fast-growing open source databases and applications like MySQL and SugarCRM, respectively, are increasingly popular as hosted services, MSPmentor has noted.

The challenge for MSPs is trying to figure out whether to build out hosted data centers, or to leverage third-party hosted services like Amazon EC2 or Google Apps, or Master MSP hosted services from such companies as Ingram Micro Seismic and Do IT Smarter.

Even traditional MSP platform providers such as Kaseya say they will now offer network operation center (NOC) and hosted services, in an attempt to assist MSPs with 24×7 customer support and other gap services.

Right now, it’s sometimes easy to overlook how online companies like Amazon.com and Google are gradually moving into the SaaS worlds. But as SaaS and managed services continue to converge, MSPs will need to adjust their business strategies accordingly.