According to the ABA Journal, a New York Judge allowed a Wife to serve her husband with a divorce summons via facebook.
To be clear, changing your facebook relationship status from "Married" to "Single" won't start the divorce process in Colorado. To get divorced in Colorado, a spouse must file a case. Before a Court has the authority to grant a divorce, the Court must find that the other spouse was properly served. In Colorado, these procedures are found in Rule 4 of the Colorado Rules of Civil Procedure.
Ordinarily, spouses voluntarily "accept" service by signing a document accepting that they are on notice of the case. But occasionally a spouse does not agree to accept service and requires the filing spouse to formally serve him or her. Personal service is ordinarily accomplished by a process server who hand delivers the documents to the person being served. There are special rules in cases where the other party is outside of the state of Colorado. In some cases, tracking down a person can be costly.
In rare cases, the other spouse cannot be found. Fortunately, Colorado law allows spouses filing for divorce to serve their spouse through other means, by, for example, publishing notice in a newspaper. The divorcing spouse in the New York case proposed a creative way to serve her husband -- by sending the notice through a facebook message.
The determination of whether service is adequate depends on the particular facts and circumstances of each individual case. Moreover, a Colorado Court may have jurisdiction to grant a divorce but lack jurisdiction to enter Orders respecting children and/or dividing property.
Every case is different; be sure to consult with a qualified attorney if you need legal advice about this issue.