If you are updating PHP on your production server, beware of relatively new max_input_vars php.ini directive which is now 1000 by default. That means if you have 1001 form field - only 1000 form fields will be submitted. Use of this directive mitigates the possibility of denial of service attacks which use hash collisions in connection with CVE-2011-4885.
From php changelog:
2012-01-03 : security / trunk - Added php-5.2-max-input-vars patch max_input_vars directive to prevent attacks based on hash collisions - CVE-2011-4885
Why we have so much form fields is a subject for different post. The main problem is that even php site says this update is available from PHP version 5.3.9. The fact is we have 5.3.2-1ubuntu4.14 and the update is there.
So... you know... beware. :)