[RickM]

I would have her use her best judgment on notice.

If her current customer is fine with her leaving two weeks (or earlier) then she should have no problem working that out.

If she feels the task at hand may take more than 2 weeks to wrap-up or hand off she should be able to work out with both parties and leave knowing she did the right thing.

In the past I've had consultants leave with two months (or more) notice. I really needed them to complete a project and we worked it out all the way around.

Bottom line is to be up front and professional. There's nothing like either side feeling stranded.

Best of luck to her.