Apparently, you can't have a commonly used verb as a trademark or something.
Google could not claim copyright over the phrase by virtue of the principle established in
Exxon Corp v Exxon Insurance Consultants International Ltd [1982] 1 Ch 119. I.e. the phrase is too insubstantial to be considered to fall within the requirements for material which is protected by copyright.
It shouldn't be a problem though, because they came first; the verb comes from them, they didn't steal the verb.
However, as Adi has suggested, there does not appear to be a problem with Google obtaining a trademark for the phrase. This is because, as Adi said, the phrase is unique and was used by Google first. This satisfies one of the primary requirements for trademarks, the phrase is inherently distinctive. Moreover, there is no doubt that this phrase is capable of distinguishing Google's goods and services from other corporations (in this case, search engines). These facts are likely to give Google a strong argument for making the phrase a registered trademark.
