The full changelog can be found here. The high points for the 4.0.10 maintenance release include ....
GUI: fixed disappearing settings widgets on KDE hosts (bug #6809)
Storage: fixed hang under rare circumstances with flat VMDK images
Storage: a saved VM could not be restored under certain circumstances after the host kernel was updated
Storage: refuse to create a medium with an invalid variant
Snapshots: none of the hard disk attachments must be attached to another VM in normal mode when creating a snapshot
USB: fixed occasional VM hangs with SMP guests
USB: proper device detection on RHEL/OEL/CentOS 5 guests
ACPI: force the ACPI timer to return monotonic values for improve behavior with SMP Linux guests
RDP: fixed screen corruption under rare circumstances
rdesktop-vrdp: updated to version 1.7.0
OVF: under rare circumstances some data at the end of a VMDK file was not written during export
Mac OS X hosts: Lion fixes
Mac OS X hosts: GNOME 3 fix
Linux hosts: fixed VT-x detection on Linux 3.0 hosts
Linux hosts: fixed Python 2.7 bindings in the universal Linux binaries
Windows hosts: fixed leak of thread and process handles
Windows Additions: fixed bug when determining the extended version of the Guest Additions
Solaris Additions: fixed installation to 64-bit Solaris 10u9 guests
Linux Additions: RHEL6.1/OL6.1 compile fix
Linux Additions: fixed a memory leak during VBoxManage guestcontrol execute
Bob Netherton is a Principal Sales Consultant for the North American Commercial Hardware group, specializing in Solaris, Virtualization and Engineered Systems. Bob is also a contributing author of Solaris 10 Virtualization Essentials.
This blog will contain information about all three, but primarily focused on topics for Solaris system administrators.