Markspace's press release on Jan. 30 says a couple of interesting things, and here's a snippet:

Unfortunately, our testing has shown that versions 5.0 and prior of The Missing Sync for Palm OS do not function completely on the new Intel-based Macs. At this time, those products are not supported for Intel Macs.

Mark/Space has already announced an upcoming 5.1 release of The Missing Sync for Palm OS, a free update for owners of version 5.0. Version 5.1 will be a universal application, meaning that it will run natively on Macs with either an Intel or PowerPC processor. Version 5.1 is expected to be available as a public beta soon, with final release scheduled before the end of March.

I don't know whether "do not function completely" means that it does function partially. Anyone out there try it yet on an intel iMac?

The snippet is from their main intel page:
The full press release is at: