Non-blocking libpq in 7.3 beta2

Hi,

I noticed that the nonblocking code in the 7.3beta2 version of libpq
has been modified to fix the broken return values of PQflush, amongst
others.  

A couple of questions:

Is the nonblocking code comprehensively fixed and just awaiting beta
testing, or is it a temporary patch?

Can I use this 7.3 beta2 version of libpq against a 7.2.1 version of
the pgsql server?  It seems from various list archives that the
backend/frontend protocol has not changed so far (though it might for
7.4).  If so, then the answer should be affirmative, correct?  If not,
is there a non-beta version that the server that is usable against
this libpq?

Thanks,

--prashanth