If you use Amazon's AMIs they do a lot of updates for you. Recently, they updated their AMI for the bash and SSL security exploits. If you have a permanent instance, you would have to run some updates yourself, but if you use auto-scaling, you can just update the group and then when the instances cycle, the new updates will be applied.
This is also the case with Ubuntu (the most popular Linux distro). The AMIs get updated regularly.
Not for their hosted version management solution, I assume.