One of the best features added to GeoGebra 4.0 (still in Beta) is graphing inequalities. The image below were sample inequalities graph plotted in version 220.127.116.11, which, as of this writing, can be downloaded here. So far, the latest GeoGebra Beta can only graph linear inequalities. The feature is till very unstable, so updates may cause for it not to work properly. Michael Borcherds, lead developer of GeGebra, told me that they are not yet sure if polynomial inequalities will be included in the 4.0 version.
GeoGebra 4.0will probably be released late this year or early next year.
Thank You GeoGebra Team.