I admire Dr. Perelman for his work (even though I don't completely understand the proof), but most of all I admire him for his integrity. He withdrew from mathematics because he felt dishonesty was tolerated and he didn't want to be part of it. He refers to Shing-Tung Yau of course:
"I can't say I'm outraged. Other people do worse. Of course, there are many mathematicians who are more or less honest. But almost all of them are conformists. They are more or less honest, but they tolerate those who are not honest."