For anyone using the iPad for any document collection (including company PDF manuals), the Good Reader app + Dropbox is the way to go.

Dropbox is a secure online file syncing service that offers 2Gig of online storage free (more space is available for a fee). Good Reader for the iPad connects with your Dropbox account and syncs effortlessly.

The workflow is as follows:

Download or place any files that you want to sync to your iPad into the Dropbox folder on your computer. In Good Reader, select the folder and press "sync". All the files on your computer are copied to your iPad - so easy a pilot could do it.

I'm guessing that the Delta iPub service is a shared online folder similar to what I described above. If you have an iPad and you don't have Good Reader, you're missing out!

Get 2 Gig of free storage from Dropbox here
Here's the Good Reader user manual talking about auto file sync