Didn't want to hijack the other thread, but one way of getting software to users rather than machines is to use Microsoft Softgrid.
Basically, this virtualises an application (so you can easily have multiple versions of Office, Internet Explorer installed which wouldn't normally be possible) and runs it in a way where it can't interfere with other apps (but can interact with them in "proper" ways - eg copy/paste, DDE, OLE etc.
To make it work you have a softgrid server which "streams" apps to the users on demand (but caches the stuff on the workstation so that after initial load there's little network traffic). To get the streamed app, you use a sequencer program (a bit like WinInstall) to capture the install process but the advantage is that the first run on a workstation is very quick (<1 minute for Word 2007, for example)
You can install the softgrid client on every machine (it's an easy MSI) but software appears per user (or group of users) so a group of users can be given an application and it will appear on which ever machine they use but it won't appear for users not in the group.
The only downside of Softgrid is the licensing - you can't just buy it; it comes as part of software maintenance.
Also useful is Instant Applications - open source apps, pre-streamed for Softgrid (thanks to someone else on here who pointed that out to me!)
Anyone using this or tried it on Terminal Services yet? Can you use it with thin client devices in this configuration? Information is a bit sketchy, but from what I read, in a TS environment softgrid will virtualise the application on the TS server which prevents issues with application compatibility, meaning you should be able to get even tricky apps running in a thin client environment.