Apple just released iTunes 9.1, which according to the release notes brings several new features and enhancements such as support for synchronization iPad eBook content including customization and greater Genius Mixes.

It is available via Apple Software update and 97.3 MB in size.
According to the release notes, iTunes 9.1 includes several new features and improvements such as:
• Synchronization with iPad to enjoy your favorite music, movies, TV shows, books and more on the go.

• Organize and sync books you've downloaded from iBooks on iPad or added to your iTunes library.

• Rename, rearrange or remove Genius Mixes.

There are also rumors that iTunes will start a section of new books. According to Apple you can replace the current "category audiobooks" on iTunes, with a more comprehensive "Books" section. The new section is expected to make it easier to organize content by just viewing the ebooks that are compatible with the device to be synchronized.

You can download iTunes 9.1 from this link or via Apple Software update.