As joomla 2.5 was released, it seems they actually have a built in update feature . I used Akeeba Admin tools to upgrade my site to 1.74 (as 2.5 was not an option yet) and then plan on upgrading from there. As a side not. #rd party apps will have to be upgraded to. Best course is to disable them before upgrade and plan carefully.
Here is their post on new features.