what can see cloaked units?

[NOiZE]

In XTA nothing both cloaks and is stealth, however your own jamming towers jams your own radar also. So cloaked units only works well when the opponent has his own base jammed, and the easiest way to detect a suspected cloaked unit is to disable jamming in that area (or make sure to build your base with some gaps in the jamming coverage).

mines are both stealth and cloaked in XTA

[Soulless1]

they should make it so that EMP blasts disable cloaks.

Then you could use spies (which I am told self-d with an EMP blast...?) to hunt spies

Actually, it would be pretty cool if spies just had an ability which revealed enemy spies. There'd be a whole intelligence/counterintelligence side of the game then.