Rakshit Patel has posted a tip to the Programming Facts blog that those out there wanting to upload larger files through your application - change your settings via one of three ways to tell PHP it's okay.
I have seen many developers who find difficulties when working with larger files upload in php. When files which are too large in size [...] If you are uploading file which is larger than 2MB size than here i am showing you the way to upload larger files using PHP.
The method's pretty much the same in each of the three methods. You can either have the settings in your httpd.conf (if you have access to it), in the php.ini or in a .htaccess file in the directory your PHP script is in.