Kezzie - I don't believe your statement is correct, at least according to my interpretation of the literature.
Employeres have a responsibility to obtain a copy of legal documentation that verifies what you fill out on the I-9, which includes 1 item from list C. If the employee provides a SSN that states there are restrictions, such as those SSA puts for ppl on temp. greencards, the employer has an obligation to following up with an employee to make sure that their legal authorization has not expired or is not restricted - hence the reason they ask for the greencard.
Note that most employers don't do this, but a lot do...just because they ask to see the green card, it doesnt mean they're violating your privacy...they're just following the directives of USCIS and the I-9 form.
QUOTE(Kezzie @ Feb 23 2008, 01:37 PM)

To start with your employer has no legal right to ask to see your greencard... they can ask you to complete a I-9 and all you need are a State Drivers licence or ID card and a Unrestricted SSN....
see instructions for I-9
http://www.uscis.gov/files/form/i-9.pdfTypes of Employment Discrimination Prohibited Under the INA
Document AbuseDiscriminatory documentary practices related to verifying the employment eligibility of employees and the Form I-9 process are called document abuse. Document abuse occurs when employers treat individuals differently on the basis of national origin or citizenship status in the Form I-9 process. Document abuse can be broadly categorized into four types of conduct: 1) improperly requesting that employees produce more documents than are required by the Form I-9 to establish the employee's identity and work authorization; 2) improperly requesting that employees produce a particular document, such as a "green card," to establish identity or work eligibility;
http://www.uscis.gov/files/nativedocuments/m-274.pdfKez