EMC has not yet revealed the nature of this announcement, but says it will be one of the most important in its history and have "a significant impact on enterprise computing and the way companies approach information infrastructure." A speculates that this announcement could be the highly anticipated refresh of EMC's flagship storage system, which last received a major overhaul in mid-2007 with the release of DMX-4.

EMC will make its announcement during an online presentation Tuesday titled "." EMC promises to discuss "the evolution of the virtual data center, storage requirements for the next decade, and new EMC capabilities that enable you to bridge the divide between physical and virtual environments." Next month, EMC will host its annual conference in Orlando, where it discusses new product announcements and trends in the storage market.

Meanwhile, the EMC-owned virtualization company, VMware, is planning an , promising that "virtualization is about to take another giant leap." VMware says the announcement involves Cisco and Intel and will help advance cloud computing and dramatically increase the efficiency of IT.

VMware has promised to unveil its much-touted sometime this year, but has not said whether it will be revealed on April 21. At least some of the capabilities of the Virtual Datacenter Operating System are expected to be part of , the code name for VMware's next major hypervisor release.