IBM recently made its most significant cloud computing announcement to date, which one executive compares to the launch of Big Blue's venerable System/360 mainframe 40 years ago. Following is my list of the top 10 things you need to know about IBM's emerging cloud strategy.1. IBM is taking a three-pronged approach to cloud computing, with a focus on the enterprise market. It's offering workload-specific public cloud services, complementary hardware appliances for on-premises deployment, and consulting and systems integration services to help companies build private and hybrid clouds in their data centers.

2. IBM is partnering with Google to provide cloud services to university researchers and with Amazon to deliver IBM software (DB2, Informix, WebSphere Portal, Lotus Web Content Management) over Amazon Web Services, but IBM won't be competing directly with Google App Engine or Amazon's EC2 in the cloud services market.

3. IBM's first cloud products/services are aimed at software testing and virtual desktops, to be followed by a cloud appliance for analytics and other appliances.

4. The cloud computing market will grow to $66 billion by 2012, with more than half of that going toward private clouds in corporate data centers, according to IBM.

5. Key to IBM's approach is a "service management system," based its Tivoli line, that enables standardized services, automated provisioning, and self-service capabilities.

6. IBM researchers are doing application prototyping and other cloud development on the company's Research Compute Cloud (RC2), which has been used for hundreds of projects.

7. IBM's first-generation CloudBurst appliances are based on its BladeCenter HS22 Intel-based blade servers. IBM plans to offer cloud appliances built on its other hardware platforms, including its Power processor-based systems and Z series mainframes.

8. The cost and ROI of IBM's cloud offerings will require some research by IT departments; IBM touts cloud computing as a way to lower capital costs, licensing fees, and operating expenses, but it hasn't published a price schedule as detailed as Amazon's for EC2. As one price point, IBM's CloudBurst appliance costs $207,000.

9. IBM has 13 cloud computing centers around the world, where businesses, government agencies, and researchers can design, develop, and test applications for deployment in cloud environments.

10. IBM envisions partner clouds with built-in analytics where business partners share data and applications, and semi-private clouds in which companies share IT infrastructure with trusted partners. So far, however, the company hasn't detailed plans to offer such services.

For a more in-depth report and analysis, see InformationWeek's newly published "IBM's Cloud Computing Strategy Defined." It's free; registration required.