EDIT: Actually, I was right.paronomasiac said:That's not actually correct. Color identity is defined by any mana symbols in the cost and the rules text. (And color identifiers and CDA's.) Quagmire Druid [http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=27188]'s color identity is Black and Green. There is no card in all of M:TG which has a color identity of black that can target enchantments.SL33TBL1ND said:Not technically true. There's a mono-black zombie druid which can, but the activation cost is in green. His colour identity is still black, though.
Edit: Okay, that's not entirely accurate. Vampire Hexmage [http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=192232] can target enchantments. The enchantment remains a permanent, but it definitely has its uses.
From the comprehensive rules:
202.2. An object is the color or colors of the mana symbols in its mana cost, regardless of the color of its frame.
So it doesn't include abilities.