Several people at dark sites have reported the comet as faintly visible to the naked eye, making it a record-breaking fifth such comet in 2004, following NEAT (C/2001 Q4), LINEAR (C/2001 T7), Bradfield (C/2004 F4), and LINEAR (C/2003 K4). Recent brightness estimates cluster around magnitude 5.5, almost half a magnitude brighter than predicted, and the comet sports an extremely faint dust tail one or two degrees long as well as the ion tail shown in the photograph above.
Update: Just before midnight on December 13th, Night Sky editor J. Kelly Beatty got a good look at the comet from his home northwest of Boston. He noted that while it was easy to spot in his 7x35 binoculars, Comet Machholz was marginal through a 6x30 finder and impossible to see naked-eye in his suburban sky (which has a limiting magnitude of about 4.) He reported no hint of a tail.