Ksplice - Ksplice Uptrack
http://www.ksplice.com/uptrack/

Ksplice Uptrack is a new service that lets you effortlessly keep your systems up to date and secure, without rebooting. Once you’ve completed the easy installation process, your system will be set up to receive rebootless updates instead of traditional, disruptive updates. Learn more.

Ksplice Uptrack is a new service that lets you effortlessly keep your systems up to date and secure, without rebooting. Once you’ve completed the easy installation process, your system will be set up to receive rebootless updates instead of traditional, disruptive updates.

This software lets you update your linux system without the need for a reboot. Looks pretty promising, available for ubuntu now.