My Van Houtte coupons that are older are without the restrictive wording. I think I got them before Christmas!
I also have stacked goldfish, alymers, VH steamers, Olymel chicken, Stagg chili, catelli, Enfamil formula, Similac formula, Goodstart formula, Heinz baby food and toddler food, pampers (have tons of stackable coupons) wipes and diapers, etc. in the past (most recently on the weekend).
Again, you just have to look at your coupons. I have noticed that coupons that I used to be able to stack are now printed with restrictive wording that prevents stacking. P&G has been for awhile but within the last month I've also noticed that Enfamil and other formula coupons have incorportated the same restrictive wording.
Just have to wait for really good sales now.