I had to buy a new thermometer (left mine at the hotel last week - oops!). Written all over the package is "CONCEPTION AID ONLY. NOT TO BE USED FOR CONTRACEPTIVE PURPOSES".
I find this funny as temperature only really helps to confirm that you may no longer be fertile. It can't confirm when you are ovulating, only that you have already ovulated. Really, it's not the best tool to use for trying to conceive (on its own). It's only used for analyzing your timing after-the-fact. So, to call it a tool for conception and NOT contraception is a bit silly.
I also find it sad that the reason they put that warning is that they don't trust the NFP method or the users of the method and want to cover their arses in case someone gets pregnant while trying to avoid. It gives us NFPers a bad rap. For the record - Fertility Friend also has these warnings on their site, likely for the same reasons.