Q:

How to handle Eclipse in a multiuser environment (500+)?

How would you go about handling Eclipse in a multiuser and multisite environment with, say, 500 or more developers? 
Having each one downloading their own installation would lead to a support and maintenance nightmare. 
Forcing each one to use a central installation doesnt feel ideal either and would limit the users option to download plugins.
Edit: the question is not about forcing user to choose Eclipse, the premise of the question is that there are 500+ users who want to use it as their IDE. 
If this many user are to handle their own installations, there will be alot of time wasted just downloading Eclipse and installing it with some required plugins. Say it takes half a day for each user, multiply that by 500 or more and that means alot of wasted time/money.

A:

The best solution will be Yoxos Ondemand Eclipse + Maven
Yoxos has capabilities of creating templates of IDEs which you can distribute or update.
In some of the big java shops, they create their own edition of Eclipse (add plugins, tweaks etc), make it available on the local intranet and ask to run a bat/sh script to install: 1. Sun JDK, 2. Eclipse, 3. Source code control etc
If you don't want to handle all that, then the best option would be Yoxos.

