http://www.uscis.gov/graphics/formsfee/forms/index.htm#chart
At the beginning of the page:
NOTE: Effective 7/1/06, Form I-485 for employment-based adjustment of status applicants, filed together with Form I-140, or filed alone, based on an approved or a pending Form I-140 is filed at the Nebraska Service Center, regardless of the applicant抯 place of residence.