Uhm, there are a couple of things. One, merely being out of status does
not preclude getting an advance parole. The operative term is "unlawful
presence." With tourist and most non-immigrant visas, there is a
certain time with which the alien can remain in the US lawfully (i.e.
the date stamped on the I-94). Beyond that date, the alien begins to
accrue unlawful presence which is counted towards the 3 or 10 year bars.
If the overstay is less than 180 days, there are no bars, and MOSTLY one
can use advance parole without a hitch. 180 days or more, you're better
off not leaving the country while waiting for AOS.
Story is different
for F1s who are admitted with D/S. Go look for those threads; they've
been discussed extensively in this newsgroup and others.
Lastly, a
student visa still requires a non-immigrant intent, and the consul will
look at your ties to your home country. I know of several potential
grad students who were denied F1s because they did not have sufficient
ties to their home country (family, etc). The fact that her spouse is
in the US will probably make it difficult for her to get an F1.
But
then again, nothing ventured nothing gained.
Caveat: I am not a
lawyer, and this is merely my opinion. I've been through the process
(just got my GC last week), and I'm speaking mostly from experience and
from anecdotal evidence I've gathered while researching the process. My
post does not presume to be absolutely correct in every detail.