From Fedora Project Wiki
USB Emulation
- Support for USB 2.0 (EHCI) devices has been added.
CDROM Emulation
- Many fixes to comply with the ATAPI specification
- GET_EVENT_STATUS_NOTIFICATION: Implement 'media' subcommand that helps report tray open/close, media present/absent states to guests. Newer Linux guests (kernels 2.6.38+) rely on this command to revalidate discs.
- Major code refactoring and cleanup
Upstream release notes
- Update to qemu 0.15, refer upstream changes at http://wiki.qemu.org/ChangeLog/0.15
Xen
- Xen support merged into qemu
x86
- Stable guest TSC across migration
- Support for VIA CPU features
General
- Several memory leak fixes in all virtio devices
qemu-img
- The performance of qemu-img convert has been improved
- qemu-img convert and rebase now support the -p option which enables progress display
qcow2
- Improved the performance of creating/deleting internal snapshots
Guest Agent
- Added the guest agent that supports snapshotting,