How is this done? 8 separate images and then merged in PS somehow?
Pretty much exactly that. In CS4&5 (not sure about 3) you use the Photomerge tool under Automate and Photoshop goes into a half hour plus spasm whilst it processes the end result.
I've used it with reasonable end results for producing sequence shots of horses jumping, but usually find that a bit of fine tuning is needed to adjust the final image.
With that in mind, can I make a couple of suggestions Alex?
I'd mask out the last position of the bowler, as it doesn't really add that much (maybe cropping out the Mid Off as well), and I'd also try to find the ball in the last two captures and bring it back in again, to show the flow of the movement and action.
As Dods says the background is a bit confusing, but to maintain the realism there is not a great deal that you can do about it....
Except.... I'd be tempted to do a second version to sit alongside the original, with
all of the background masked out and just the bowler showing on a plain white canvass (or maybe mid grey given the cricketing whites!). It would be quite a bit of extra work, but worth it in the end I'd reckon. Think of it as an Eadweard Muybridge like panorama!
Nice photo all the same!