A new resultnew result shows how to generate single block MD5 collisions, including an example collision:
> md5sum message1.bin message2.bin
> 008ee33a9d58b51cfeb425b0959121c9 message1.bin
> 008ee33a9d58b51cfeb425b0959121c9 message2.bin
There is an earlier example of a single block collision, but notthe technique for generating it was not published.