University of New Hampshire's Center for Venture Research has posted its 2008 1H summary of Angel investing statistics. The key points for me were:
Angels, as an investing class, put more money to work in first and second round investments than VC's
At least during 1H of '08, Angels were investing more dollars than in '07
As expected, and quite different from the venture business, Angels do not invest deeply (multiple rounds) in companies they fund. Preferring to spread the dust wide, rather than deeply. I have not seen any studies showing returns for the Angel class, but suspect the unwillingness to pile capital into the winners (and having full exposure to the losers), greatly hinders overall returns.