Twopence is (will be) a remote execution engine for tests, able to run tests in virtual machines and real hardware through various means of communication : virtio for KVM / QEmu, ssh on top of libssh, serial lines. This library can be called from shell and ruby wrappers.
While it is already functional (and used), it still needs polishing, stabilizing, and extending. It is also planned to integrate it with Pennyworth (project Machinery) and let it go fully Open Source.
Currently, the usual way to communicate with VM instances in the cloud from outside is ssh. This is okay for most uses, but a) does not work when you mess up with the guest's ability to network and b) requires a free floating IP.
I wonder if, for qemu/kvm instances, it would be possible to use virtio-serial possibilities : from the guest, it is seen as a serial port, and from the outside, it is seen as a UNIX socket, or as something else. It is fast, as it does not go through virtualization and device drivers.
Paracuke is a toy project whose first use was to make it easy to run tests in parallel from coroutines. It's an implementation of Cucumber in Go.
Now I would like to see if I can add random tests sequence shuffling and, in case of a failure, reduction to minimal sequence: John Hughes - Don't Write Tests, Generate Them - YouTube.