Sorry to bump this thread back up, but I just made a post in the Linux forum that might be useful to anyone trying to get a C-motech card working on a 15" MacBook Pro:

A slight update to this: I finally got around to trying the dongle with the MacBook Pro and a powered USB hub and it works perfectly, so the problem definitely seems to be the amount of juice that a MBP can send to its ports.

After a bit of reading I found out that the USB standards specify 500mA and 5v, a regular MacBook has a single controller with 1000mA and 5v available to it and can split the current (ie one port at 600mA and one at 400mA) as required to its two ports but the Pro is more rigorous in its implementation of the USB standards and has two controllers that will supply the standard 500mA and 5v to each port, but no more.

I guess the C-motech draws more than that so I will have to buy a Y cable or a powered USB port to use the dongle regularly with the MBP. It's a bit of a bummer, but at least we know now why it won't work on the MBP.

Or at least on *my* MBP.

Once the Songkran silliness is over I will be going back to the Apple shop in Jungceylon where it was bought and following up on this.

On mine, it will not work on the left USB but it does on the right one. Didn't know about the split mechanism. The MBP definitely has a problem with USB devices that draw too much power, shame. It seems like most PCs - and other Macs - happily supply much more power than specified in the official USB spec.

A USB ExpressCard - if such a thing exists - would probably work too..