Stefan Esser has posted a warning about upgrading PHP to the 5.2.7 release :
(…)a change in the ext/filter extension that by default processes all incoming data, broke the magic_quotes_gpc feature. While magic_quotes_gpc itself is deprecated and it is recommended to not rely on it as protection against SQL injection, it is still used in many legacy applications that become very insecure once it is turned off. And exactly that happens with the upgrade to PHP 5.2.7. The fix for this was already commited to the PHP CVS and PHP 5.2.8 will be released next week.
I just fixed this issue in the Dotdeb packages, just upgrade your servers.