One of the big attractions of iOS 4 for many of us is the opening of iBooks to PDFs that you can add. It's done in a parallel universe: your iBooks are divided into books and PDFs as you see here. (Look at the top left of the screen.)
Like many aspects of the operating system, iBooks is smart enough not to show you nothing. You may not see PDFs in the upper left if you don't have any, but once you add PDFs, you'll see them.
As you probably noticed, iBooks is now available for iPhone if you're running iOS 4. Reading between the lines, this means that books (including PDFs) are now full-fledged iTunes entities that can be synced across all of your devices with iTunes.
So the next step is to move to iTunes and load up some PDFs.
Notice that the Library at the left of iTunes now has a category for Books at the left. If you look carefully, you'll see that no device is connected to iTunes: I'm just working on my computer, and I haven't yet synchronized with other devices.
In the center of the window, my PDFs are shown in a grid view. You'll see that you can change this view as you wish. But first, you'll need some PDFs.
Adding PDFs is very simple.
First, pick a PDF to upload. Then, in iTunes, choose File->Add to Library and select the file. It will move to the Books folder.
If you're tired of menu commands, drag the PDF file to the Library section at the top left of the iTunes window.
Alternatively, if the Books section is selected, drag the PDF file to the center of the window.
As always, when you're dragging an item the destination is highlighted. If you're heading for the wrong place, just release the object somewhere that isn't highlighted (like a background or the toolbar at the top of the window).
Now you should have your PDF in your library, but you'll see that I've done some other organization, and it's not a bad idea to do so yourself.
Switch to the list view. That's where you can see how the PDFs are organized.
To set this up, select your PDF. (You can do that from the grid view--the list view is just to show you the data and how useful it can be).
With the PDF selected, choose File -> Get Info (command - i). The name of the document will already be there. You can add an author (in the Artist field) if it's not there.
I usually fill in the Grouping and the Genre which will be the Category for books.
Now you can synchronize your iTunes library with your iPad. Connect it as always and go to the Books tab; choose to sync books -- either all or selected.
After you've completed the sync, your iPad will have the books and the categories. And you can start reading.