I sent the following via feedback, fyi:

When clicking 'Add marriage information' from the Family view pages, the url generated is:
http://trees.ancestry.com/pt/EditPerson.aspx?pid=-XXXXXX&...

When it should actually be:
http://trees.ancestry.com/pt/Event.aspx?tid=XXXXX&pid=-X...

Also currently, adding a spouse does NOT add a marriage event, AND when attempting to add a marriage event, it will not be added if all 3 information fields are blank even though a selection button for the current spouse is checked. (A work-around is to add 'unk' or something in the Location or Description fields, if a date is unknown)

My suggestion would be to have the proper marriage event boxes display immediately after adding a spouse, so that a marriage (or some sort of union) is registered for the couple.

No union causes major problems in the otherwise excellent (imo) Gedcom Export.

So as not to mislead anyone with my previous post.. the exported gedcom does show a union, but still only a marriage if some information is in any of the 3 fields. But the gedcom is currently a semi-non-standard output that does cause some issues. The good news is that it's only an issue with php-gedview and TNG (as far as I know) so it's probably only of interest to a small number of people.

My comment about the wrong link when adding a marriage in Ancestry still stands, and I (at least) think it's a bug.