You may have missed it, but the first line of the Nationals press release actually revealed something very interesting about the nature of Bryce Harper's contract. According to the release, Harper will receive a Major League contract, not a Minor League contract.
The Washington Nationals tonight agreed to terms on a Major League contract with College of Southern Nevada outfielder Bryce Harper, the first-overall selection in the 2010 First-Year Player Draft.
This is significant because it immediately adds the 17-year old Harper to the 40-man Major League roster. To be clear, this doesn't mean he's going to be playing in the Majors next season or anything. Calling him up now would mean he would be eligible to face arbitration sooner. But teams traditionally offer Major League contracts to players they believe will rise through the minors quickly rather than slowly.
Clearly, they feel Harper will be in the Majors far sooner than we expect.