New York court holds that email exchange satisfies the statute of frauds and results in settlement, no big surprise (New York Medical Malpractice Blog):

In Williamson v. Delsener, NY Slip Op 01333 (1st Dept. 2009), the Appellate Division, First Department held, in a dispute over the terms of a settlement, that “e-mails exhanged between counsel, which contained their printed names at the end, constitute signed writings (CPLR 2104) within the meaning of the statute of frauds (citations omitted) and entitle plaintiff to judgment (CPLR 5003-a[e]).

The NYMM Blog adds a cautionary note: 

Therefore, if you, in a legal context, agree to something in an email which you send with your standard, printed “signature” at its end, courts will consider the agreement to have been reduced to writing, and it may well be viewed as part of an enforceable contract. So, add this to the myriad reasons why you must be careful before pressing your “send” button.

I received a quick and harsh education in this five or so years back. 

We represented a plaintiff in a copyright infringement case, and the parties originally had a licensing arrangement which was cancelled by the defendant.  When plaintiff found out defendant used the tracks anyway, we sent a nastygram to defendant(s), who forwarded this letter to their lawyer.  We were clearly in the right and I hoped the dispute would settle quickly, and short of litigation.  I had a few email exchanges with the opposing lawyer in an effort to settle, and it seemed like we were close to settling.  I was always careful to put in all emails that there was no settlement until there was a written (paper) agreement signed by both parties.  However, in an excess of courtesy, in one email, I wrote in response to a question from defendant(s) that "an ongoing license would not be a problem" (or that it "should not be an issue").  Later in the case, defendants latched on to this to argue all sorts of things, including that we had granted a license, and acted in bad faith.  Defendants also tried to take my deposition over this.  These tactics were unsuccessful, but they clued me in to the fact that emails sent or received in the settlement context can be used against you. 

The same is true of all emails I guess.  Settlement emails are no different.

(NB:  I hope this does not cause New York lawyers to add to the text of their (I'm sure already bloated) email disclaimers.  That would be an unfortunate byproduct of this case.)