While 2011 wasn't a year of historically huge tech merger and acquisition deals, activity was nonetheless vigorous. Google alone bought more than 20 companies, while the likes of HP, Oracle, SAP, Dell, and Microsoft rounded out their mature product portfolios with acquisitions. Among the strongest riptides in enterprise IT M&A: software as a service (SaaS), mobility, big data, and social networking.

What follows, in reverse order, is one editor's take on the 10 most important (though not necessarily the largest) enterprise IT acquisitions of the year. Not included on this list are the big OEM-oriented deals: Western Digital's $4.3 billion deal to buy Hitachi Global Storage Technologies, for instance, or Texas Instruments' $6.5 billion acquisition of National Semiconductor.

10. VMware and Socialcast: Virtualization market leader VMware isn't immune to social business fever, acquiring Socialcast, a maker of cloud-based communications and collaboration software that mimics "the interaction style of social networks, but with the security, management, and integration functions of an enterprise system," as my colleague David Carr reported in May. The Socialcast deal (terms weren't disclosed) followed two other cloud acquisitions by VMware: slideware maker SlideRocket in April and open source email software maker Zimbra in January 2010.

9. SAS Institute and Assetlink: This acquisition (no price tag was disclosed) isn't top 10 tech M&A material unto itself, but it's important in the context of the red hot trend it represents: the move by CMOs to apply analytics to their ad campaigns, promotions, social outreaches, and other marketing programs in order to prove and refine their effectiveness. Assetlink makes "marketing resource management" software, used to plan and budget ad spending, manage the content, create workflows, and manage leads. Its acquisition by SAS, announced in February, follows like-minded deals by IBM (it shelled out $480 million for Unica in October 2010) and Teradata ($525 million for Aprimo in December 2010).

8. Dell and Force10: Dell's acquisition of switching vendor Force10 Networks (financial terms weren't disclosed), following its $960 million deal in December 2010 to acquire storage virtualization vendor Compellent Technologies, enhances its credibility as a big league data center supplier, alongside Cisco, HP, and Brocade. Force10's market share is small--just 1%, according to Dell'Oro estimates around the time of the July 2011 deal--but its technology is considered first rate and Dell will bring it to many more customers.

7. Microsoft and Skype: Among the biggest tech deals of 2001, Microsoft's $8.5 billion acquisition of Skype is also emblematic of one of the biggest CIO trends: the consumerization of enterprise IT. The lines between business and consumer IT are blurring, and Microsoft is looking to capitalize on that trend by integrating the consumer-oriented Skype videochat software with its enterprise unified communications and messaging platforms. Speaking of consumerization, will 2012 be the year Microsoft finally lands Yahoo?

6. Oracle and RightNow: It's almost as if Larry Ellison plunked down $1.5 billion of Oracle's money to get back at a former protege, Marc Benioff, whose Salesforce.com and its cloud-based services have been stealing most of the thunder in enterprise software. Within weeks of his orchestrated rebuff of Benioff at the Oracle OpenWorld conference at San Francisco's Moscone Center, Ellison announced Oracle would be acquiring RightNow, a leading maker of SaaS-based customer service and management apps and a semi-competitor to Salesforce.

As my colleague Chris Murphy noted in a story on the RightNow deal, "Oracle, one of the tech industry's most acquisitive companies, isn't too concerned about overlapping products when it comes to buying into hot markets." Oracle had previously introduced its suite of enterprise software, Fusion, with a cloud-based option for CRM, as well as a hosted version of its PeopleSoft software licensed on a per-user, per-month basis.