"Disposable VMs will be very lightweight VMs that can be created and booted in a very short time, say < 1s, with a sole purpose of hosting only one application, e.g. a PDF viewer, or a Media Player," Joanna Rutkowska, Invisible Things CEO, said.
The basic idea is that you can quickly create a disposable virtual machine to read e-mail attachments or perform a specific task. When you're done, you can just throw it away.
Developers are closing out existing tickets for the Alpha 2 milestone. Rutkowska said that the Beta 1 release is expected after the summer holidays.