Can EEM detect the IOS version of a device, compare it to a user defined value, and send a trap if the device's IOS version does not match the standard?
You could, but boy what a lot of work that would be - and I don't think it would be a good solution.
You are far better to use an SNMP tool to collect the information and then report on it.
Cisco Prime can do that for you under the PSIRT reporting tool from 3.0 and up and also check for vulnerabilities in the versions you have
As Philip said, yes, EEM can do it. The applet policy wouldn't be that complicated, either. The trouble will be you'd need to deploy this on all your devices. And if you had a config management tool already, chances are you have an inventory manager that could report on this across all of your devices.