When the Windows 8 beta first launched, the Start button had been integrated.
But on the latest Windows 8 “Consumer Preview” version, the button has disappeared entirely, according to pcbeta. No one knows why Microsoft took this action, but it seems that from now on the old Start button will be invisible and replaced by a “hot corner” (invisible section) that will have the same functionality as the Start button. For Windows 8, once you open/touch this section, the new Metro interface will pop out on the screen.
If the Start button disappears, what will happened to the hardware Start button? According to winsupersite, we should be calm because every Windows device (PC, laptop, tablet, phone) is required to have a hardware Start button.
Some speculate that Microsoft might reintroduce the Start button if there is enough demand, but for now, it remains invisible. Windows 8 is rumored to be released at the end of 2012 (RTM version), with an official announcement in the first months of 2013, though Microsoft hasn’t confirmed this.