Cupping has become increasingly popular over the last decade, especially with swimmers.
The body of evidence and research for cupping is not as large or strong as for acupuncture and massage (largely because it just has not been studied enough!) There is some evidence that cupping can relieve pain and provide therapeutic benefits through a range of different mechanisms.
However, there is a large amount of anecdotal evidence from a range of athletes, coaches and trainers that cupping improves their recovery and appears to provide some therapeutic benefit. So if its good enough for the Olympians it may be good enough for the rest of us!