I have a few additions to this.

Section 'Administrator Account running your Setup Package'

Vista and 7 has compatibility mechanisms that detect keywords like setup, install, update in the exe name and project description (file properties) and will automatically elevate such a process. This is good and bad. Good it makes old installers work (most of them) without the need to do right click > Run as administrator, but on the other hand if you named your exe or project something like "InfoUpdater" it will be automatically elevated every time which you will most likely not want to happen.
Aside how stupid this thing is, MS also never provided a way of downgrading the privilege level. This means that if an application running with admin rights shells another application, that other application will be launched with admin rights too. On the other hand, applications running as standard user can request elevation of a process to admin level (followed by the UAC prompt).

There are also changes in the way how Services work. They now run in a separate, isolated, session 0. This means they can no longer have any interaction with other sessions (Desktop). Services can't shell applications, they can't show any windows or messages, but they have unrestricted access to protected areas of the file system and registry (except the HKCU hive).