The words you added change it drastically.

It's difficult not to infer the rest, considering your contradictory history. My apologies.

its traditions as well as its corruption fixed in stone for hundreds of years.

Remember, it took them 500 years to apologize to the long dead Galileo for being right.

To admit women as full human beings would rock that organization off its foundation, never mind giving women access to the priesthood and beyond.

I'm not even sure how such a thing would work.

Wouldn't one lose the authority to complete the act midstream somehow? And what would be the motivation?

This sounds like shoddy reporting to me. Many more details are needed to fill in the details of exactly how this works.

I don't know anything about the actual procedures involved in excommunication, but this just sounds fishy to me.

Basically it's incurred when the action is expressly prohibited by Canon Law, with this explicit penalty, and the person, knowing this, proceeds regardless. Another example of this would be the deliberate desecration of a consecrated host.

Here's wiki.

http://en.wikipedia.org/wiki/Latae_sententiae

That's different from excommunication ferendae sententiae which is imposed by a bishop.

The former can be lifted by the sacrament of confession by a priest. The latter can be lifted only by the bishop.

...trying to think about the subtleties involved gives me a bit of a headache.

It seems misleading for the article to suggest that the excommunication was an act performed by the individual in question, rather than an act imposed (under whatever theory) by the church on her.

There is a jure or ab homine. If you complete an act that forbidden you are excommunicated by law (a jure). You can also be excommunicated by a "judge" (ab homine) which is, perhaps, the process you are thinking about. You can be excommunicated eo ipso (by the act itself). It is pretty clear that I have been excommunicated a jure (eo ipso) for my beliefs and statements of heresy.

This might mean there are many, many excommunicated women out there, who don't know it.

Those who get abortions are not really told this; they are told to go through some kind of "reconciliation" process, as I recall.

Some items (and I believe abortions are one of those) allow for the excommunication to be revoked with reconciliation. Others need to have a hearing.