QUOTE (Spiffy @ Mar 16 2008, 10:13 AM)

I've never heard to open the tabs before Shabbos; what I have heard, and what we do is not close the diaper with the tabs in a nice little package before we throw it out since it's pretty unlikely it's going to come apart and it's more of a permanent nature.
QUOTE (greentiger)
It's not only the tabs. From what I understand the diaper itself is lightly glued closed and you need to unfold it before shabbos. I got this from home and I really don't know how known/practiced/nessecary it really is.
Unsticking before shabbos is nessecary though and should also be done with female personal hygiene products that will be used over shabbos.
Depends whom one asks.
In terms of removing the plastic backing on diapers, bandaids, female personal hygiene products, etc,
R. Ribiat writes "the veracity of a lenient ruling on this this questions seems quite clear" because
1. the tabs are merely protective to keep the gummed surface clean, without any intention to create adhesion
2. the tabs are glued temporarily, regardless that the consumer uses it months after manufacture
3. there's no makeh bepatish since you're just removing the item from a protective covering rather than making it now functional
That said, R. Ribiat still says, "one shold nevertheless open the tabs before shabbos if possible" because of stringent dissenting opinions that indeed it's tofair [tearing].
As for re-taping a dirty diaper before throwing it out, there too he says some are lenient but "it is better to be stringent and avoid retaping the diapers after use".
ArtScroll, the final arbiter of all things Jewish, similarly essentially says it depends whom one asks. In
The Shabbos Home, volume 1, he says some are stringent, but quotes R. Moshe Feinstein as permitting removing the tabs from things like band aids, which also applies to things like diapers and female personal hygiene products.
As always, ask one's own local orthodox rabbi and don't rely on the rantings that I derive from general ignorance and stalk-trolling internet fora.