According to a Intuit spokesperson, Quicken Online Mobile lets users "easily manage their money on-the-go with the only app that gives them a forward looking view into dollars coming in versus bills they have yet to pay – enabling them to make intelligent real-time spending decisions."
For example, the app can show whether there's enough in the bank to cover a proposed purchase after existing commitments are accounted for.
And if the purchase does go ahead, the transaction can be categorised on the spot instead of waiting for it to appear in the bank records.
Other features include showing the location of nearby ATMs (though apparently not by using the iPhone's GPS capability) and identifying those belonging to your own bank to avoid surcharges.
There's no indication that Intuit will provide an iPhone app that works with the desktop version of Quicken, for example to support classification at the time purchases are made.