It's only been approximately a year and a half since the first 1TB disc drive* got to make the marketplace. Hitachi was the first to bring out its 1TB HDD in January of 2007.
Just this week Hitachi brought out its second generation 1TB HDD with a 43% power savings equated to the first generation. The Hitachi drive applies 3 discs to bring the 1TB capacity and economize energy. Nowadays, Seagate declared the world’s first 1.5TB desktop disc drive known as the Barracuda 7200.11 1.5TB.

As you are able to gather by the name, the drive spins around at 7,200 RPM and applies four discs to gain the massive 1.5TB capacity. Seagate says that this is the biggest growth in store capacity in the latest 50-years and the 500GB growth in capacity is thanks to improved perpendicular magnetic recording technology.

Along with the 1.5TB 3.5-inch desktop HDD, Seagate as well declared new 500GB 2.5-inch HDDs for use in notebook computer*. The 500GB notebook computer drives will ship in 5,400 and 7,200 rpm varieties. The drives are called the Momentus 5400.6 and Momentus 7200.4 HDDs. The 5,400 RPM drive applies an 8MB memory cache and the 7,200 drive has a 16MB memory cache.

Seagate executive VP and general manager of PC Business Michael Wingert told in a statement, “Organizations and consumers of all kinds worldwide continue to make, share and consume digital content at stages never before seen, giving rise to new markets, new application program* and requirement for desktop and notebook computers with unprecedented storage capacity, performance and reliability. Seagate is committed to powering the next generation of computing nowadays with the planet’s quickest, highest-capacity and most reliable storage solutions.”

Seagate declared in 2006 that it expected capacity of HDDs to hit 2.5TB by 2009. The Seagate 1TB HDD was declared a bit over a year ago in June 2007.

[Source]