Atomic - 12:19 am on Jul 28, 2008 (gmt 0)
Think of it as trying too hard. Put the same targeted keyword in the title tag, description, keywords, H1 tag, in on-page text, image alt-tag, as anchor text in a link, in bold, italics, yada, yada, yada, 950 penalty.
I've done some of this for ages without any problem. I don't, however, misuse the alt tag or go crazy with italics and use of bold. Perhaps that's saved my skin.