Parallels just released an update to Parallels Desktop 8 for Mac, the No. 1-selling software for running Windows and Mac applications side-by-side on a Mac without rebooting, which includes experimental support for the latest developer preview of OS X Mavericks.
By updating to the latest build of Parallels Desktop (build 8.0.18494) and following instructions in the Parallels blog post (link below), developers who are registered members of Apple’s Developer Program can run Parallels Desktop 8 on OS X Mavericks and run OS X Mavericks in a virtual machine in Parallels Desktop 8 for Mac.
Parallels Desktop 8 for Mac – which also supports the desktop virtualization of Windows, Mountain Lion, Lion, Linux, Chrome OS and more – enables software, mobile and web developers to safely and simultaneously test a variety of operating systems as guests, as well as well as develop and test applications on them without risking their development machines.
More info about Parallels Desktop 8 and OS X 10.9 Mavericks here.