Per the FreeBSD 9.0 release process, the first beta snapshot was expected to be out on the 20th of July. More than a week later, the ISO images for the various architectures are now being found on mirrors (e.g. here), but no official release announcement for FreeBSD 9.0-BETA1 has yet been found.
The release process also had a second beta planned for the 3rd of August, but that will surely be delayed due to the late availability of beta 1. This process also had a third beta due in mid August and then two release candidates in late August. The FreeBSD 9.0-RELEASE build was expected to be completed on the 7th of September. Due to the late arrival of FreeBSD 9.0-BETA1, this final release date may be pushed back but at least it still will hopefully be on track for a christening in September.
I haven't had the time yet to try FreeBSD 9.0-BETA1 or any earlier snapshots of FreeBSD current, but among the planned work for FreeBSD 9.0 included ZFS as the default file-system, SSD TRIM support, 802.11n high throughput support, more ATA/CAM improvements, PCI hot-plug support, S4 hibernation support, Xen Dom0 support, Linux 64-bit binary support in FreeBSD/amd64, proper EFI booting support, properly supporting LLVM (the Low-Level Virtual Machine) next to GCC, user-land D-Trace support, better Oracle VM VirtualBox support, faster reboot support, and much more.
Some of the work for FreeBSD 9.0 is talked about on this FreeBSD.org Wiki page.