VirtualBox 3.1.0 (released 2009-11-30)

This version is a major update. The following major new features were added: 

Teleportation (aka live migration); migrate a live VM session from one host to another (see the manual for more information) 
VM states can now be restored from arbitrary snapshots instead of only the last one, and new snapshots can be taken from other snapshots as well ("branched snapshots"; see the manual for more information) 
2D video acceleration for Windows guests; use the host video hardware for overlay stretching and color conversion (see the manual for more information) 
More flexible storage attachments: CD/DVD drives can be attached to an arbitrary IDE controller, and there can be more than one such drive (the manual for more information) 
The network attachment type can be changed while a VM is running 
Complete rewrite of experimental USB support for OpenSolaris hosts making use of the latest USB enhancements in Solaris Nevada 124 and higher 
Significant performance improvements for PAE and AMD64 guests (VT-x and AMD-V only; normal (non-nested) paging) 
Experimental support for EFI (Extensible Firmware Interface; see the manual for more information) 
Support for paravirtualized network adapters (virtio-net; see the manual for more information) 
In addition, the following items were fixed and/or added: 

VMM: guest SMP fixes for certain rare cases 
GUI: snapshots include a screenshot 
GUI: locked storage media can be unmounted by force 
GUI: the a log window grabbed all key events from other GUI windows (bug #5291) 
GUI: allow to disable USB filters (bug #5426) 
GUI: improved memory slider in the VM settings 
GUI: the VirtualBox website couldn't be opened from the help menu (bug #4559) 
3D support: major performance improvement in VBO processing 
3D support: added GL_EXT_framebuffer_object, GL_EXT_compiled_vertex_array support 
3D support: fixed crashes in FarCry, SecondLife, Call of Duty, Unreal Tournament, Eve Online (bugs #2801, #2791) 
3D support: fixed graphics corruption in World of Warcraft (#2816) 
3D support: fixed Final frame of Compiz animation not updated to the screen (#4653) 
3D support: fixed incorrect rendering of non ARGB textures under compiz 
iSCSI: support iSCSI targets with more than 2TiB capacity 
VRDP: fixed occasional VRDP server crash (bug #5424) 
Network: fixed the E1000 emulation for QNX (and probably other) guests (bug #3206) 
NAT: added host resolver DNS proxy (see the manual for more information) 
VMDK: fixed incorrectly rejected big images split into 2G pieces (bug #5523, #2787) 
VMDK: fixed compatibility issue with fixed or raw disk VMDK files (bug #2723) 
VHD: fixed incompatibility with Hyper-V 
Support for Parallels version 2 disk image (HDD) files; see the manual for more information 
OVF: create manifest files on export and verify the content of an optional manifest file on import 
OVF: fixed memory setting during import (bug #4188) 
Mouse device: now five buttons are passed to the guest (bug #3773) 
VBoxHeadless: fixed loss of saved state when VM fails to start 
VBoxSDL: fixed crash during shutdown (Windows hosts only) 
X11 based hosts: allow the user to specify their own scan code layout (bug #2302) 
Mac OS X hosts: don't auto show the menu and dock in fullscreen (bug #4866) 
Mac OS X hosts (64 bit): don't interpret mouse wheel events as left click (bug #5049) 
Mac OS X hosts: fixed a VM abort during shutdown under certain conditions 
Solaris hosts: combined the kernel interface package into the VirtualBox main package 
Solaris hosts: support for OpenSolaris Boomer architecture (with OSS audio backend). 
Shared folders: VBOXSVR is visible in Network folder (Windows guests, bug #4842) 
Shared folders: performance improvements (Windows guests, bug #1728) 
Windows, Linux and Solaris Additions: added balloon tip notifier if VirtualBox host version was updated and Additions are out of date 
Solaris guests: fixed keyboard emulation (bug #1589) 
Solaris Additions: fixed as_pagelock() failed errors affecting guest properties (bug #5337) 
Windows Additions: added automatic logon support for Windows Vista and Windows 7 
Windows Additions: improved file version lookup for guest OS information 
Windows Additions: fixed runtime OS detection on Windows 7 for session information 
Windows Additions: fixed crash in seamless mode (contributed by Huihong Luo) 
Linux Additions: added support for uninstalling the Linux Guest Additions (bug #4039) 
Linux guest shared folders: allow mounting a shared folder if a file of the same name as the folder exists in the current directory (bug #928) 
SDK: added object-oriented web service bindings for PHP5