Most mianstream software includes its ID by default.
Dreamweaver gives itself away if you use templates on your pages or if you used the layout tools for creating tables and cells.
The layout tools leave telltale tags like this:
If you use any of Dreamweavers code behaviours it embeds a giveaway MM_ tag that includes other elements of the script being called.
NetObjects, Namo Web Editor, Adobe GoLive and most other editors also include a metatag at the head of the page code identifying the parent program, although you can turn this off in most programs or manually clean it up if it bothers you at all.