Another change between Squeeze and Wheezy has just come to my attention:
php5-suhosin has been dropped.
<http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=657698> has the
reasoning, but if you had it, you now need to live without it or get
compiling :)
To avoid having Apache error logs mention it a lot..
rm /etc/php5/conf.d/suhosin.ini
.. and restart Apache.
Ian