What's Microsoft's legal standing on those images? 

What was almost ok with VPCs available on MSDN is that they required me to accept special EULA that explicitly voided all and any EULAs that the MS software on that VPC might try to force me to "accept" later on. The only problem with those VPCs was that they might only be legally used to "evaluate the software and provide feedback to Microsoft" according to that special EULA, even though they were, misleadingly, I'd say, labeled "for testing your websites in IE".

I don't see any such special agreement in the archives you have on modern.ie, and the EULA in IE10 image expressly forbids to use it in "live operating environment", and I believe a test lab qualifies as such. Moreover, it requires me to "obtain a separate copies of the software, and a separate license for each copy" if I want to run multiple instances of that virtual machine. Does cloning the machine qualifies as "obtaining a separate copy with a separate license"? I doubt it.

What if a test engineer need to show the software engineer the bug he found? Can the software engineer fire up his RDP client of choice on his trusty Linux box, connect to that virtual machine and see the problem firsthand? Technically - yes, legally - no, because "Other users, one at a time, may access the licensed software running on this host pc, from any device, *but only if the remote device is separately licensed to run an edition of Windows 8 or Windows RT*". You must be kidding.

Guys, get your freaking licenses straight! 

I'd suggest something along the lines of:
This license supersede all and any license the software may display or force you to accept. This license grants you unrevokable right to run as many copies of the software in a virtualized environment, and to access the software by as many users as you wish, provided that you only use the software to test applications or web services for compatibility with the software.