Well the government itself issues money that's worth something simply because they think it is, so considering bitcoin as "money" is at least not inconsistent with what the government is already doing in this sphere. :)

Actually fiat currencies have value because the government promises to accept them for tax purposes (and for various other purposes -- fees, fines, court settlements, etc.). The government does not "think" the money is worth something; the people think the law has meaning and is worth following, and so the law gives money its value. The relationship between money and law is a major reason (maybe the only reason) that currencies tend to be neatly partitioned along international borders.