It should also work with aluminium pipe - generally anything diamagnetic with a low enough resistance to set up a really, really good eddy current.
The DC's got one of those 'repelling' pencils somewhere. It looks really neat, hovering about 1" above its holder.
@Jacob, +1 for the plastic bag trick for picking up filings - been doing it that way for years. If you're collecting grindings though, you may need a fairly thick bag. The magnet I use will perforate freezer bags with the iron whiskers if I"m not careful. The sort from ironmongery, etc. seem to work well.