From Marc Stein's Twitter:
Mavs and Wizards have completed their trade call with the league office. Deal will be announced later tonight. Seven-player swap in the end
DAL gets Butler, Haywood and Stevenson as was always the case once teams agreed Friday. WASH gets Josh Howard, Gooden, Q. Ross and Singleton
And from Marc Spears' Twitter:
Washington trade of Butler, Haywood and Stevenson to Dallas for Howard, Gooden, Ross and Singleton recently became official, source tells Y!
So much for the Butler/Jamison rumor for the Celtics. Oh well, it certainly was fun while it lasted. Time to see what else Danny might have up his sleeve.