Thanks to Mark Dubovoy and Eric Chan Macintosh Leopard and Snow Leopard users now have a usable workaround to printing targets without colour management from Photoshop CS4 and CS5.
In the interests of completeness, clarity, and good communication may I add (in brief) what I have already posted on this and the Adobe forums.
I am convinced (as a Canon Printer user) that the same issue does also effect Canon printers (despite some detractors who have yet to provide conclusive evidence of the contrary). Indeed, I would go as far to conclude that the issue, being as it seems certain to have arisen from the new Apple printer APIs, is not specific to any printer or manufacturer but will effect all printers from all manufacturers.
I can state with absolute certainty that the workaround does not work on Mac OS 10.4 (Tiger) – but I have not tested it with printers other than Canon – and that it does work on Snow Leopard 10.6.2 (10.6.3 testing to commence shortly). Thanks to you, Mark and Eric ! I can also confirm that colour managed printing from 10.4.11 and 10.6.2 produces identical prints and is not, therefore, an issue.
Mark wonders why early takers of Photoshop CS5 have not taken issue with the inability to print without colour management. Aside from weariness over the whole issue, I believe that everyone is hoping (soon) for the Adobe application which will enable untagged targets to be printed without colour management; which was announced at CS5's release. Also, of course, we have all now developed our own solutions which include the aforementioned workaround, using Preview, or printing from an earlier version of Photoshop.
I must say that the new printer APIs in Snow Leopard are a great improvement, making the whole experience of printing much more straight forward and less error prone. Once Adobe can give us the (longed-for) printing application I believe that we will have a much improved colour managed printing system on the Mac (ducks under the desk in anticipation of a deluge of posts disagreeing).