Quoting from the InnoTek official announcement:
Today InnoTek released version 1.3.4, the first significant update with over 800 improvements based on feedback from the user community.
Now Ubuntu has decided to integrate the open-source VirtualBox kernel module into the official Ubuntu Linux kernel sources starting with the upcoming Ubuntu 7.04 (“Feisty Fawn”) to further improve integration with VirtualBox, which will be hosted in Ubuntu’s software repository…
Download VirtualBox 1.3.4 here.