Mac OS X Update 10.0.1

The Software Update program checks what is available against what is in its receipts folder, as the names of the files are the same for 4L5/4L7 and 4L13 (the official update), it thinks your system is already updated. To resolve this, go to Library/Receipts and remove any ofe the pkgs from 4L5 and 4L7, then run software Update again... viola!
If you're still getting a "System Up to Date" message it may be that the site is overwhelmed. Software Update defaults to that message if you aren't let into the qeue. Try later!
Well, my receipts folder is empty, and I have tried software update numerous times over the past day, and every time I get the software up to date message. I suppose the could just be REALLY busy, but... Oh well. That's what I get for trying to be too up to date, I suppose.
Delete the SoftwarUpdate preferences file under /users/username/Library/Preferences/Software Update/

Then restart Software Update, and try the update again.
Thanks for your help, but unfortunately It's still not working for me. I'll probably try reinstalling if it doesn't start working shortly. Or maybe I'll just wait until I can get the update without using Software Update. Bound to happen eventually.
The first meathod worked fine for me... Did you delete *all* of the things that the installer put on ("10.0.1Update.pkg", "SoftwareUpdate131.pkg" and "EpsonPrintDrivers.pkg")?

Software Update is happily downloading right now for me... Thanks PlaidPJs!
Don't feel too bad, because it doesn't seem different, correct me if I'm wrong (but don't kill me for it), from 4L7 (except the build version in About This Mac). I can't see a difference, anyway.