I love the way Toodledo handles sorting in its web implementation: Up to three independent criteria, hierarchically ordered (e.g. Sort by Due Date > Sort by Folder > Sort by Priority).
In the iPhone app, on the other hand, all we get is an arbitrary set of pre-combined criteria. For example, while "Sort by Due Date and then alphabetically" is provided, there is no way to rearrange the criteria ("Sort alphabetically and then by due date").
Toodledo developers, do you plan to make sorting on the iPhone work the same way as it does on the web?