Selected answers from the Dumb SEO Questions Facebook & G+ community.
Perry Bernard: There are SEO advantages for absolute (stating the whole URL) and build advantages for relative (stating only the page path). For SEO, go with Absolute.
Richard Hearne: They most certainly are not. is a relative URL which will be located relative to the browsers current location. If the user is currently in the /about-us/ folder, that link would resolve to /about-us/mytargetpage.hml. would be root-relative. That preceding / makes a big difference.