Since OS X Lion was released, if you wanted to build a Hackintosh (and I would like to think the tutorial on this site is the most comprehensive how-to out there), you had to get your hands on a copy of Snow Leopard, install that, and then upgrade to Lion. There were often complications along the way, to the point where I refrained from upgrading to Lion. Thanks to tonymacx86, however, hackintoshers can now grab Lion from the Mac App Store and install it natively from a USB drive. Here's the blurb:
Introducing UniBeast- our new tool to create a bootable USB drive from your Mac App Store purchased copy of Install Mac OS X Lion or Apple Store purchased OS X Lion USB Thumb Drive. This all-in-one bootable USB drive can also be used as a rescue boot drive for system recovery. UniBeast + MultiBeast is the easiest method to do a clean install of Mac OS X Lion or update any Snow Leopard system. The following guide requires no coding, terminal work, or Mac experience of any kind.
The How to Build a Hackintosh guide has been updated with this latest info.