lol, that's a lagging indicator, it's not relevent for price forecasting.
Not to mention, once we have reached a certain amount of saturation (a certain % of the general population knows what bitcoin is) the google trends charts are virtually meaningless.
If I had a bitcoin every time some newb posted a google trends chart and pretended that he could predict future price with a lagging indicator...
EDIT: "buy bitcoins" not so bad last 90 days:
http://www.google.com/trends/explore#q=buy%20bitcoins&date=today%201-m&cmpt=q
