The Gutmann method has been widely misunderstood, not least because the work Peter Gutmann did in the mid-1990s is not really applicable to today's hard drives. The best information currently available is that, for all practical purposes, a single pass erase will serve as well as the 35 pass Gutmann erase. Reducing erase times (which are, by the way, limited by the capability of the hard drive more than anything) to 1/35th of what they would have been is a very significant bonus.
As to whether erasing (and especially free space erasing) damages the drive, there is no evidence to that effect. I tend to take a more conservative approach than Joel and argue that excessive use (for example erasing free space of a drive every day) is probably best avoided on grounds of general caution. But that may be just prejudice on my part; there is, as I said, no actual evidence on the subject one way or the other.