Looks like people can still go outside the match till at least 2005.
http://www.nrmp.org/
More specifically:
http://www.nrmp.org/postponenewrule.pdf
Board Postpones Decision to Implement New Rule
The National Resident Matching Program (NRMP) Board of Directors at their recent annual meeting postponed a decision on a new policy that would standardize the rules of participation for all applicants. Presently, the rules for participation in the Main Match for U.S. medical school seniors and those for “independent” applicants are dissimilar. NRMP participating institutions (hospitals and residency programs) can accept U.S. medical school seniors only through the Match. However, independent applicants (osteopathic school seniors, U.S. citizen graduates of foreign medical schools, and international medical graduates) may register for the Match and continue to seek a position outside the Match - and – may accept a position outside the Match in an NRMP participating institution.
The decision was postponed pending the outcome of the NRMP’s current investigation of the feasibility and desirability of conducting a second match to alleviate some of the disorganization associated with the post-match scramble. A decision to conduct a second match could affect implementation of the new rule. The Board will reconsider its decision regarding the new rule at its May 2005 Board of Directors meeting.