Sigma first announced the 17-70mm F2.8-4 DC Macro OS HSM lens a little over a year ago, and over the last few months has started shipments of Canon, Nikon, and most recently Sigma-mount versions. The Sony-mount variant will apparently be next to ship from February 27 2010, with the Pentax-mount version following from March 19 2010. All the various mount-types for the lens have the same pricing in the Japanese market - ¥56,200, approximately equivalent to US$620 (ignoring exchange rate fluctuations, taxes and duties), and in all cases a lens hood is included in the price.
The Sigma 17-70mm F2.8-4 DC Macro OS HSM lens is one of several optically stabilized lenses that the company has made available for the Sony Alpha and Pentax K lens mounts. It's an interesting strategy, and one that makes Sigma unique in the marketplace, with none of the its competitors offering stabilized lenses for either mount. At first glance the decision might seem curious, given that both Sony and Pentax's cameras feature body-based image stabilization. However, both stabilization techniques have their own strengths and weaknesses, and by offering stabilized lenses, Sigma is providing Sony and Pentax photographers with an alternative stabilization option, allowing them to select between either body-based or lens-based stabilization as the shot conditions dictate.
The Sigma 17-70mm F2.8-4 DC Macro OS HSM lens is priced at $680 in the US market. More details can be found on the Sigma Corporation of America website.