If you are using Boot Camp Control Panel to restart the Mac, you will see a button that says "Restart into Mac OS X". If you press it, your Mac will restart into Mac OS X. If you don't want that, restart the Mac from Start button.
Also, if you want to start always into Windows 7, open Boot Camp Control Panel select the Boot Camp volume, press Apply and close this program
I open the Boot Camp control panel in Windows 7 and select the the Boot Camp Windows disk. Next to the Restart button I see it tells me it will restart in Windows. When I click the button there is a dialog box that asks if I want to restart in Windows. I hit OK and it restarts in MacOS.
Ever since I installed Windows 7 some years back this process has worked incorrectly. I waited, expecting Apple updates to Boot Camp would resolve the problem. Does anyone know a solution?