Billings, a time tracking and invoicing app for the Mac, has undergone a seemingly minor update in preparation for a very useful feature: iPhone sync. Last week, to Apple for App Store approval last week, and the primary focus of this week's update to the desktop version is to support the syncing of clients, work slips, and invoices to your iPhone or iPod touch. Both the Mac and iPhone clients were in beta testing for the last couple months, and I was fortunate enough to help for a bit. Billings Touch is a gorgeous, useful companion to its big brother, and syncing was pretty easy to set up.

Besides the big new feature, Billings 3.5 can perform better with large databases, and it now supports mailing invoices with , the desktop Gmail client. Users can now also print invoices with a "paid" stamp on them, however one casualty was lost on the journey to Billings 3.5: support for Mac OS X 10.4 Tiger.

Billings 3.5 is a free update for existing owners, and a free demo is available for 10.5 Leopard and 10.6 Snow Leopard users. A license costs $40.