How to display a message to all Endpoints

There isn't a messaging feature built in, but you could use the "Download and run a file" or the "Run a DOS command" to run a script to pop up a message.  Something like this:
http://stackoverflow.com/questions/774175/how-can-i-open-a-message-box-in-a-windows-batch-file
 
The other way you could do that is with GPO, using the same idea.  Does that help?

Hello!
I did not spend a lot of time attempting this but when I tried using a batch script to display echo commands, the cmd window is never displayed to the user due to cmd running as a system process not user process. This causes it to run in the background unfortunately. 
What I did not attempt was to use a VB  script which may just acheive this...
 
If anyone has the time to test this, I would be very interested...
 
Thanks all, happy testing!

Why not use the MSG command? 
Pull up the web console, select your endpoint.
Go to Agent Commands - Advanced
Select Run Dos a Command and put the following in the field:
MSG /w <username> hi there
Send the command.
I don't know if you can do that to multiple endpoints at once but it should work one at a time (just play with it and see).  You might be able to do that to whole groups.  Not Sure.
 
Hope that helps,
Steve B.

Thank you for all your ideas. I will have to experiment to find the easiest method. One of the problems is how to be 100% sure all Endpoints viewed the message. I will add this as a Feature Request. 

in the agent commands there is a feature to "view commands for selected endpoints" which will show if the msg command has executed or not. 
The /w is a wait flag which will require the user to click OK to get rid of the pop up.
 
Short of a new messaging feature, this should do what you want (albeit that "all endpoints" part I'm not sure about).  I know this will let you message one endpoint (I'm unwilling to play around with my users in the middle of the day to see if you can select mulitple but my guess would be yes).
 
Play around with it if you have a couple of unassigned workstations/laptops with WR installed.

Good suggestion @ 
 
You could also do an email with read receipt, or an online form that requires them to acknowledge that they've read it.  Then you can go hassle the people who don't read it 🙂

Did anyone have success with these methods?
I have tried:
Command Line with MSG
Standard Batch File with Echo messages and pause at the end
Batch file that copies itself to the startup folder
VBscript with message
Batchfile that launches our website
 
Nothing has worked.
Any ideas?

Have you talked to support yet about this?