A homebrew coder has managed to get Left 4 Dead running on a PS Vita, thanks to clever use of the PlayStation Mobile (previously known as PlayStation Suite) programming toolkit. Whether it's actually running on the device or streamed from a remote windows server isn't entirely clear - we suspect the latter due to an IP address entry screen appearing at the start of the video - but there appears to be little in the way of lag or graphical compromise. Even the Vita's gyroscope has been incorporated into camera control.
PlayStation Mobile is designed to allow indie developers to design and test games for Vita and PlayStation-certified Android devices, and we hope that more officially-approved apps will soon be available. Whether Sony will crack down on homebrew applications like this, however, remains to be seen.