I was reading the USCIS performance report for March 2009 and came across an interesting statement. Not sure if this has been posted before....
http://www.uscis.gov/files/nativedoc...ce_mar2009.pdf
"Last year, we began issuing Employment Authorization Documents (EADs) for a two year period instead of one to these employment-based applicants to their renewal burden.
In the next EAD renewal cycle we anticipate incorporating advanced parole authorization into the EAD, also for a two year validity period."