VirtualBox 4.3.0 is out and VM teleporting is working.

To try it do the following:

1. On the Source machine Create a VM on a shared storage. I used this home server sharing a ZFS volume via samba.

2. on the target machine create a VM using the same settings and use the .vdi disc created in step 1. Ensure ALL settings are the same. If you are using floppy drives they need to be accessible from both physical systems, however it's easier to delete floppies. I don't think they even exist anymore anyhow.

3. On the Source system start the VM as normal. You can start an app or anything you like.

4. on the target machine issue the following command: VBoxManage modifyvm <targetvmname> --teleporter on --teleporterport <port> .  This modifies the VM to wait for a teleport instead of starting right away. now Start the VM. You will see it waiting for a teleport input instead of starting right away. in this example the command is:
C:\Program Files\Oracle\VirtualBox>VBoxManage.exe modifyvm solsbi2_teleport --teleporter on --teleporterport 6000

5. on the Source machine issue the following command: VBoxManage controlvm <sourcevmname> teleport --host <targethost> --port <port>. 

in this example the command is:

C:\Program Files\Oracle\VirtualBox>VBoxManage.exe controlvm solsbi2_teleport teleport --host 192.168.111.177 --port 6000

Watch the transfer happen. ;-)

Read more below:

Target host: 192.168.111.177

then start VM

on Source host:

Machine appears running on target host.