From the Canon developer page:
PLEASE NOTE: The Macintosh version of SDK 6.0.1 supports EOS digital SLRs only (EOS-1Ds, 1D, 10D, D60, D30, Digital Rebel). Canon Inc. has informed us that they are dropping Mac OS SDK support for PowerShot cameras introduced in 2003 and going forward. We will continue to offer Mac OS SDK 5.0.0 for PowerShot cameras with USB interface introduced before 2003.
This doesn't affect end users directly, but it does affect those who use third party applications developed for the macintosh platform. This is upsetting to see, and I hope that anyone concerned about equal support for the Macintosh and Canon will email their customer service department and let their opinion be heard.
Development of one nifty macintosh application that I am working on has effectively stopped with this announcement.
I don't know if this is a forebringer of other support being dropped on the Macintosh as well, but it's not a good sign.