Pumpkin -- I haven't tried a sensor hack yet, but I wouldn't be surprised if it could use a small tweak. The most obvious situations where I would want to use it would require me to send my fleet in to break a few tachyon posts so the Hacker can slip into the planet safely, which will already stir up the guards and potentially expose my fleet to whatever it was that I'm trying to hide them from (OMD, Arachnid posts, etc). And if there are any Ion cannons, you can't try to skip breaking the tach posts first since they'll just splat the Hacker as soon as it comes in, before it can re-cloak.
The 30 sec delay before it kicks in kind of hurts it if you are bringing it in to disable a command station that does planetary tachyon coverage, as the enemy fleet will definitely already have engaged your fleet in that time, and it'll be tricky to time getting every ship of yours to stop firing the instant the hack finishes to keep them from immediately breaking their cloak. If that delay were reduced, I could see myself giving this a try when I needed to split my fleet and strike several targets on a planet at once, as it would be faster and more flexible than wrangling a flock of Cloaker starships.
Mal -- Interesting idea on using it to cover escape from impending Special Forces murder, that sounds like it could work well to save slower-moving ships at the end of a huge fight when the transports have long been vaporized.
Idea directed at no one in particular -- Wouldn't it be cool to have a DE-cloaking hack? That would be handy in attacks on Stealth Master AI planets, or saving your life in the face of a massive stealth attack on one of your worlds. The latter would save you from having to EMP your own units. This should probably be more expensive than the Sensor hack though so it doesn't render the Tach sensor/drone or the couple of ships that have short-range decloaking pointless.