Another possibility is OmniFocus. It's an expensive app (£23.99 in the UK or about $40, I guess - I can't 'see' the US app store), but it allows you to set up several project management, task assignment, To Do lists and sync them using a cloud service, like Apple's MobileMe. So you could set up your employees' tasks/projects/milestones/deliverables etc etc and then sync them remotely over the (mobile) Internet. As they 'tick off' completed tasks/work packages etc you could remotely upload what they'd completed and look at their work load, upcoming critical deliverables/milestones/targets and adjust them over the Internet if you thought that was needed.
It's quite a 'complex' program, but the OmniFocus website (link in the app store) has a PDF User Manual on-line, so you can see what it's capable of before you buy. It's got some good reviews too.
Whether you'd be prepared to spend $40 per employee is another matter....
Great to see iPads making it into the business community.
Tim
Scotland