Instead of only showing / hiding the placeholder we made it possible that the opacity of the hint gets reduced when the user focus an input. Only when he starts typing the hint really disappears. (Chrome implemented a similar behavior in newer versions. Or to be precise it was implemented by Webkit changeset 121529)
The big advantage behind this is that the user still sees the hint so he knows what to enter whereas a solution just hiding it helps not that much (besides the fact that the page looks nicer on rendering).
Communication and discussions are important and even further necessary to find the best solutions since normally nothing is perfect from the beginning. Relying ONLY on browser features is the easiest and nicest solution from a technical point of view. But as a professional developer you always try to find the best thing that makes everyone happy. =)