PalmSource’s decision to drop Mac compatibility from Cobalt (formerly known as Palm OS 6) is, on the surface, maddening. But this cloud may have a cobalt-thorium G silver lining.

Cobalt will have a different PIM architecture that renders it incompatible with the current Palm Desktop. The current Palm Desktop for Mac, however, sucks — and sucks hard, and the HotSync Manager is only barely on speaking terms with iSync. Mark/Space has already announced that it will release a version of Missing Sync for Palm Cobalt devices — they’ve made or announced similar software to get Sony Cliés, Pocket PCs and Danger Hiptops to sync up with a Mac. They might, in other words, come up with a solution better than anything PalmSource could come up with.

It also raises the question: assuming that the PIM architecture is readily accessible to third parties (as HotSyncing is not), why might not Apple itself engineer Cobalt compatibility directly into iSync? At least one commenter in the Palm Infocenter story’s comments raised that possibility, drawing an analogy with Microsoft ending IE development as Apple released Safari.

The problem this time is that the alternatives aren’t in place in time to reassure nervous consumers. There are almost certainly a lot of pissed off Mac/Palm users out there today.