Hindawi's open access journals' average impact factor is up over 27% in the last year.
Here's an excerpt from the press release on liblicense-l:
Hindawi Publishing Corporation is pleased to announce that it has seen very strong growth in the Impact Factors of its journals in the recently released 2008 Journal Citation Report published by Thomson Scientific. This most recent Journal Citation Report shows the average Impact Factor of Hindawi's journals increasing by more than 27% over the past year, with two of Hindawi's largest journals, EURASIP Journal on Advances in Signal Processing and Mathematical Problems in Engineering, rising by 70% and 45% respectively. . . .
In addition to the 14 journals that were included in the 2007 Journal Citation Report, three of Hindawi's journals received Impact Factors for the first time this year: Clinical and Developmental Immunology, EURASIP Journal on Wireless Communications and Networking, and Journal of Nanomaterials.