MUSTANG is a 90 GHz bolometer camera built for use as a facility instrument on the 100 m Green Bank radio telescope (GBT). MUSTANG has an 8 by 8 focal plane array of transition edge sensor bolometers read out using time-multiplexed SQUID electronics. On the GBT each pixel has an 8″ beam size. In one hour we expect to be able to map a 15′ square of sky to 0.2 mJy/beam RMS making MUSTANG on the GBT a very competitive instrument capable of a wide range of galactic and extragalactic science. In September 2006 MUSTANG had first light and became the first instrument to use the GBT at 90 GHz. During two months of subsequent testing we showed that MUSTANG behaved as well on the telescope as it did in the lab. Observations were made of many astronomical sources including Saturn and the star forming region W3.We were able to confirm our beam shape and different observing strategies were tested. Procedures were put in place for pointing and focusing and a data analysis pipeline was set up. Several problems were identified during commissioning and are currently being addressed. One of these, excessive 1/f noise, has already been solved and we plan to take our first science observations in late 2007.