Infested Command Center
An Infested Command Center is a rarely seen building that is produced when a Queen uses Infest Command Center on a damaged Command Center. The Command Center must have less than 750/1500 HP to be infested. The Queen will enter the Command Center for a short time (Spell Range is 0), and come back out with the Command Center infested. Upon being infested, the Command Center is set back to full HP. It retains its ability to lift-off and land and can be landed on Zerg creep. The terran player can avoid infestation of a command center by quickly repairing it.
Using Scourge Support
One ZvT trick based on "Infest" ability is that when Terran flies with his Command Center to an empty resource location you can quickly attack CC with 7 Scourges and infest it with the Queen. Even if Terran immediately destroys the Infested CC, his planned expansion will be strongly delayed. Similarly, you can use this move when the Terran lifts off his Command Center to avoid an attack. This use presupposes a surplus of Gas, but for example Zero used it against Hwasin .
Neutral Command Center on Holy World
On the recent OSL map Holy World a neutral Command Center is placed at the middle of the map. This has lead to the appearance of an Infested Command Center and Infested Terrans in professional matches, such as Kal vs. Zero and Hwasin vs. Zero from Bacchus OSL 2009.
Maps With Neutral Command Centers
Neutral Command Centers on the map make it easier for the Zerg player to infest, as it is now possible in ZvZ and ZvP matchups, and offers a Command Center that Terrans might not pay much attention to.