Deep safes offer a huge tactical advantage as they not only hide the player outside directional scanner range but also offer some strategic benefits. In nullsec wars, it has become common practice to jump capital ships to a deep safe spot or use it to jump-bridge in a support fleet in complete safety. As the safe spot is several hundred AU away, enemy fleets in the same system can't reasonably arrive in time to stop the incursion. On May 18th with the release of the Tyrannis expansion, deep safe spots will be a thing of the past. In addition to eliminating the few bugs that can be currently used to create them, CCP are updating the warp mechanics to prevent abuse of any similar bugs introduced in the future.
After Tyrannis, warps to any point over 10 AU further from the system's star than the outer-most planet will fail. This means EVE pilots are now restricted to a bubble of space centred on the star and encapsulating everything in the system. Normal safe spots within the bubble will still function but any made outside it will cease to exist. In addition, all objects in space outside the bubble will be deleted on May 18th when the expansion goes live. If you've ever left a ship floating at a deep safe spot, now's the time to go and collect it.