By default, those of us working in the web for a living tend to leave a pretty decent footprint out there. By and large I don’t see this as an issue, as it’s generally my professional work on display, which any potential employer will see eventually anyway, so I’m basically giving them a shortcut.
(Though there are potential fallbacks for people putting more personal stuff out there on Facebook, Twitter and blogs. Think of that old rule about not typing anything in email you wouldn’t want on the front page of a newspaper, then make it a public, permanent newspaper for those websites you don’t actually control.)