Windows 7 Beta has added a new feature, BitLocker to Go, which allows you to encrypt removable media like USB Thumb Drives and backup USB Hard Drives. Both Passwords and Smart Cards are supported with BitLocker to Go.
BitLocker continues to offer the same overall look and feel at boot time for protection of OS volumes. At Microsoft I use a PIN protector. I think its going to be a must for our enterprise customers.
The User Interface in the control panel provides slightly more clarification and has an option to both Turn BitLocker off and Suspend or Resume Protection. It is almost never required to Turn BitLocker off (decrypt the drive). Suspend should be used when upgrading BIOS, making OS version changes or other significant system configuration events.(i.e. moving from Vista to Windows 7, or making hardware changes). See a demo video here.