GoDaddy Shared Hosting for Linux now supports PHP 5.3!  There has been no official release on this topic, but I do not have any issues using PHP 5.3 on my shared hosting linux account.  This information was taken from GoDaddy's 4GH setup, but works for linux shared hosting as well.

To switch to php 5.3 on GoDaddy Shared Hosting follow the steps below:

1. Create a .htaccess file in the root your shared hosting account
2. Copy and paste the text between the double quotes "AddHandler x-httpd-php5-3 .php" into the file
3. Save and you are now running PHP 5.3 on your GoDaddy Shared Hosting Linux Account

Here is a quick screen shot showing that my PHP version is 5.3: