http://forum.mikrotik.com/viewtopic.php?f=21&t=98981

We are releasing a test version of an exciting new feature – Cloud Hosted Router (CHR).

It is a Virtual Machine image of RouterOS that has full functionality of RouterOS without any kind of conventional RouterOS license, with the limitation of 1Mbit per interface, in future, we will offer unlimited speed with a paid subscription. This allows you to use RouterOS in training classes, for testing, for experimentation or any other purpose, without the need for 24h trial or Demo license.

We provide a generic (RAW) format IMG that you can convert to other formats with qemu or other tools. I have already pre-converted them for your convenience to VMDK (VMware virtual disk image) and VDI (VirtualBox disk image). Those are not installers, but ready disk images.