It has been my experience that Ubuntu needs less rebooting than Windows or Mac OS X. KSplice just pushed the reboot-less nature of Ubuntu to a new level.
Ksplice Uptrack is a new service that lets you effortlessly keep your systems up to date and secure, without rebooting.
In a nutshell, Ksplice enables running systems to stay secure without the disruption of rebooting. Specifically, Ksplice creates rebootless updates that are based on traditional source code patches. These updates are as effective as traditional updates, but they can be applied seamlessly, with no downtime.
Here is a link to a paper explaining how Ksplice works.