Has an enforceable contract been formed?  If not, why not?  Is this a written contract or an oral contract?

• Scenario:  Joe wants to do some radio advertising for his acupuncture and tax preparation business.  Joe talks on the phone to a sales representative from WTOP.  After several discussions, they agree to a slate of radio spots to air on specific dates for a set price.  No written contract is signed but Joe sends the representative an email that says “Let’s move forward with this 8-week run at $9600.”  [PS: This is an actual case (with names changed) discussed on “Solosez,” the ABA listserv for solo attorneys.]

Your questions:  Has an enforceable contract been formed?  If not, why not?  Is this a written contract or an oral contract?  Does Article 2 of the UCC apply to this situation?