The short answer to someone looking for a solution: just copy over iSync from your Snow Leopard installation back to the /Applications folder in Lion, and also copy the phone plugin you need back into /Library/PhonePlugins folder. Everything will be as it was. Enjoy.
The longer story requires more explanation …
However, in the middle of the whole slew of new functions and features (“250+”), Lion is also leaving behind a few things – notably Rosetta (the PowerPC translation layer) – and the iSync and FrontRow applications.
The demise of PowerPC emulation has been long in coming, and was not really a surprise, given that it has been 6 years since Intel became the official CPU for Apple machines. The main impact really seems to be for Quicken users, which might actually be a blessing in disguise, given how pathetic Quicken really was on the Mac.
iSync has been removed presumably because it has been one of the “low usage” applications on the platform. iTunes is the center of most of the Mac based synchronization these days, along with MobileMe for the cloud side of things.
However, iSync has been a key feature of the OS for me, as I carry a non-iOS phone (a Nokia E71 actually), and being able to seamlessly synchronize my contacts and calendars with the phone using iSync made it a key part of my workflow (I even have some Automator scripts to make this easier). And iSync has been able to synchronize over Bluetooth, unlike the tethered experience with the iOS devices so far (though OTA sync is on the way with iOS 5 later this fall).
Alas, OS X Lion removes the iSync application from the hard disk once it is installed, and for a time I thought that this was end of the line for the convenience I had with the E71, and would need to go back to the darks days of manual data entry for the addresses (manual entry of calendar entries is too much of a hassle on the phone, and would need to be dropped all together).
Before installation of Lion, I had taken a full disk image of my previous Snow Leopard installation using the excellent SuperDuper! Disk cloner.
This was more from a backup and recovery perspective, but allowed me an unexpected solution to the iSync quandary – on a whim, I attached the Snow Leopard disk to the Mac running Lion, and clicked on the iSync application. Voila! iSync works exactly as it should!
In hindsight, this is not really surprising, since iSync really has been a front end for the underlying sync services (which are still around in Lion), and for managing phone and device specific plugins.
All that was needed was to just copy over iSync back into the “/Applications” folder, and also copy the phone plugins (just one in my case) to the “/Library/PhonePlugins” folder.
In summary, while Apple in its immense wisdom took out a feature that was useful to some (albeit a minority), getting it to work again was surprisingly easy. Will need to check out the situation with FrontRow next time.
[Update on July 22, 2011]
Looks like a similar recovery process exists for FrontRow as well. See this article at Macworld.