Let's talk a bit about those four lines of evidence (tell me if you are thinking of other ones.)

1.) PAH's, complex organic molecules: it is generally agreed they originated on Mars. McKay et.al. already acknowledged that they can have an inorganic origin.

2.) Nanoforms, similarly shaped to bacteria but not in size: these were already controversial before ALH84001. Their status hasn't changed since then.

3.)Magnetites: this recent report is dubious in regards to a production mechanism because of the high temperatures required. Two other recent inorganic mechanisms require hydrothermal activity which makes me suspicious there could be biological involvement.

4.)Carbonate: it is generally agreed from isotopic data these originated on Mars. McKay et.al. acknowledged they could arise inorganically. This hasn't changed.

It was all these lines taken together that led them to argue biology best explained this evidence. What evidence since then are you saying undermined their argument?

Search for Past Life on Mars:
Possible Relic Biogenic Activity in Martian Meteorite ALH84001.
http://www-curator.jsc.nasa.gov/curator/antmet/marsmets/SearchForLife/SearchForLife.htm

Bob Clark