I agree with Bernd - though without offline access via iPhone app, i can't use this app. I'm on the road, and need to track time in coffee shops, etc. Provide me with offline access via iPhone app (and the ability to sync w/ desktop app) and you have a new customer.
with my suggestion I actually did not refer to an separate iPhone app. I wanted to suggest that It would be nice if one can sync the timeline data from one Mac to an other.
but an iPhon app would be nice too ;-)
I am currently using an app called Billings. It is ok for what I do but I am getting office space and will be working from my office and from my home at different times. I would love to see a sync in the cloud so all my time is always correct on all my machines. I really love the look of this app and hope to see it develop further!