One of the most puzzling announcements to come out of the release of the T-Mobile G1 was the fact that there would be no desktop app to sync your data. While you will be able to sync you contacts and calendar info remotely (at no cost) out of the box, you must submit to storing all of the data on your Google account. Obviously, that means you must be cool with the idea of Google ruling over your personal info. It also means that the suits are not going to be happy without their Exchange support. Third party developers will undoubtedly solve this problem very quickly—maybe even by launch, but I have to ask—would you prefer the Google "cloud" approach to syncing or will you be waiting for a decent desktop app?
The cloud is awesome but I still want desktop sync also. When I upgraded my iPhone from first gen to 3G, the first thing I did was enter my MobileMe account and within seconds, I had my contacts and calendar in the phone. This was before pulling out of the parking space.
Desktop sync is useful for saving system settings, icon placement and application settings.
In a perfect world, it takes both.