Venus for most of it's existence has remained infertile and lacking of life. It was briefely explored by the older Martian civilization, and observed by the Humans. Venus has never been home to a civilization of its own.
Being the wasteland it is, Venus isn't considered a useful planet. However, an unknown Irken signal has recently claimed this planet. Although not much information is known, it is known that this signal was not broadcasted by Zim. Some theories include that this was a result of signal reflection and distortion, but some even say that this may be home to the mysterious Invader Mez.