The source code and SDK for Tizen 2.2 were released in mid-July. The update includes a number of user interface and experience updates including hardware button support. One key change is the switch to a dark theme as the new default theme. Aside from the cosmetics, it appears that battery-driven reasons drove the decision.
According to Tizen Indonesia, the dark theme will be the theme of choice for any Samsung devices that will sport an OLED display. Unlike LCD displays, dark or black OLED screens require fewer or no active pixels, thereby reducing the energy required to power the display. The switch from a light to dark coloured user interface could noticeably improve battery life. At the same time, any devices with an LCD display could easily continue to use the lighter Tizen theme without any impact to battery life (as compared to using the dark theme).
According to recent rumours, Samsung pushed out the launch of its first Tizen-powered smartphones to October or later. It is reportedly planning to launch two devices, one based on the Samsung Galaxy S III with a quad-core Exynos processor and a 720p display and another higher-end model. For its part, Samsung only confirmed earlier this year that Tizen-powered devices are coming this year but has provided few details since.
Sources : Tizen Indonesia // SamMobile