Briefly: Apple has a new version of BootCamp, actually designed to work with Windows 10. If you're already running it, look for the update in your Windows partition; otherwise, the update should be available soon. You'll need an Intel-powered Mac running OS X Yosemite to take advantage.
You could already install Windows 10 on your new MacBook or Air or Pro, but the process was a little fiddly — Apple's drivers for the trackpad, Wi-Fi and Bluetooth didn't install. This new version of BootCamp should fix up those problems.