I just found the following interesting facts compiled by Women Who Tech, which incidentally is hosting a Tele-Summit on Women in Technology on March 31st, 2008.
Top 5 Cities Where Women Work in IT
Washington, DC Metro area - women account for 32.3% of the IT workforce.
Detroit - women account for 31.5% of the IT workforce.
Baltimore - women account for 28.6% of the IT workforce.
Philadelphia - women account for 28.2% of the IT workforce.
Atlanta - women account for 28.2% of the IT workforce.