The only issue now is their PHP 5.2.4 requirement which will keep from 15-20% of the users unable to update it:
http://blog.sucuri.net/2011/07/wordpress-3-2-and-php-support...
http://blog.sucuri.net/2011/07/wordpress-3-2-and-php-support...
Which ones don't?
of those, about half are on PHP4, which you cant expect any major application to support for much longer, the rest are PHP 5.1, which whilst standard with many distro's, what's the point with droping PHP4 support if you don't choose a decent PHP5 version to start with?