Hello,
A bit confusing ...as the Screenshot provided is for SEP client and you are looking for a feature which is available on SEPM.
So to answer your question.
Is there a page where we can go to easily identify if the users SEP client versions are up to date?
Yes, you could easily compare the SEP client definitions version are up to date.
I know there is http://www.symantec.com/security_response/definitions.jsp but this doesn't give us a page to easily compare the versions on the client.
You could use the SEPM to compare the definitions from the Home SEPM page (Latest from Symantec) with the Computer Status Logs. However, there are no such features from the SEP client itself as we find in the SEPM home page.
The SEP client users have to manually compare the definitions dates from the website -
http://www.symantec.com/security_response/definitions.jsp
However a nice Idea. I have created one -
https://www-secure.symantec.com/connect/ideas/latest-symantec-feature-sep-clients
Hope that helps!!