This excerpt taken from the GPS DEF 14A filed Apr 16, 2008.
Most of our employees and those of our participating subsidiaries are eligible to participate in the ESPP. However, employees who would own stock and/or hold outstanding options to purchase stock representing five percent or more of our voting stock or the voting stock of any of our subsidiaries are not eligible. Also, seasonal employees (that is, employees whose customary employment is for not more than five months in any calendar year) are not eligible. As of March 1, 2008, approximately 130,000 employees were eligible to participate and approximately 7,800 employees were participating in the ESPP.