I'm really really sorry about not upgrading this hack, I have it upgraded in my forum and there are a couple modifications that have to be made to make it compatible with 3.0.3. theArchitect sent me a pm today and I headed here to upgrade my hack as fast as I could
I originally designed this hack for RC3 and upgraded it until gold, but I haven't had time lately to upgrade my hacks (or to document them). Anyway, I'll attach in the first post the upgraded txt for the 3.0.3 vbulletin.
About the cron job. Hourly all the orphan attachments (that is the attachments that were uploaded but the post was never commited) are deleted. When my hack is not installed then an attachment in the pm counts as a not commited attachment (that are the replacements in the cleanup2.php file). That is new behaviour in 3.0.3, in earlier versions they checked the posthash instead of the postid.
That would mean that if you upgraded to 3.0.3 and didn't upgrade the hack you might've lost your private attachments. You'd need to edit the files (or at least the cleanup2.php, then upgrade to 3.0.3 for your attachments to be safe.