I guess so. But it is a little difficult to get data from veteran people, since those figures are most often negotiated in silence. All I can see are the entry level offerings and they are in deed often below those for web-developers. I think, it is similar as in other areas -- when you manage to be seen as key-developer, you are in a much better negotiation position -- but for that, you must be either a star from the beginning or done some real great tasks in the company.