I'm not sure about for "general maintenance", but the AMT Handbook chapter on inspections has some language that piqued my interest while I was trying to sniff out an answer.
It says that:
The appropriate checklist or checklists must be utilized to ensure that no items will be forgotten or overlooked during the inspection.
The FAA feels so strongly about this they even go on to say:
Always use a checklist when performing an inspection. The checklist may be of your own design, one provided by the manufacturer of the equipment being inspected, or one obtained from some other source.
Task cards are basically a checklist (or I guess more accurately a "check book" - you go through and reference/fill out each card as you perform the task indicated, and the FAA wants mechanics to use checklists (at least on inspections, and with the standard implied OR ELSE hanging out there), so I'd imagine they're still in use in some form (though the paper / PDF product may have been replaced by something fancy and electronic).
I imagine there are some pretty slick electronic checklist/task card systems out there by now (AvPro Software seems to offer one that I stumbled on with a quick Google search, no comments on quality), but I'm just the dumb slob what flies these things and I don't know much about the maintenance end - just enough to know I know enough to be dangerous if left alone with a screwdriver :-)