Although there is no mobile open computer at the moment, I can tell you that it is something that is in development. Once we release a final product, it will be posted on our website along with an automatic notification for all Open Computing newsletter subscribers.
No release day or price has been set for any potential mobile product line. However I can assure you that at release it will be very competitively priced.
I wonder if it'll also be the first OS X notebook to include a Blu-Ray optical drive, like Psystar's other new Apple-compatible desktops.