The latest version of the Things task manager (0.9.2) incorporates synchronization and support for Leopard’s system-wide to-do’s! As has become the norm with Things, the new feature is extremely well thought-out, and in my testing so far it works flawlessly.
This was the big feature I was most expecting, since it gives me back the ability to carry some of my to-dos on my cell phone, with the ability to add new ones or check them as done.