WotLK Expertise cap pvp

[Matias66]

I have seen rogues using 2 or 3 expertise itens everywhere.
Is it really that important? What is the soft cap?

[Ruslannaforume]

26/26 for good gouge

[Whiteman]

he is asking for pvp. depends from class to class. dk gain more parry from str, then there is prot warrs, prot pala in pvp, then vs another rogue/cat etc. Its bad for pvp but then again, it can help to land some skills