I have noticed over the past year or so in the last paragraph of Kedusha of Shmonah Esrai (L’dor vador) there has been a variant pronunciations of the word V’sheevchacha. I have heard many (including respected rabbis) pronounce the word as Ooshvachacha. Can you give me any insight into this?
There is in fact a dispute about the proper pronunciation. The more common form in the siddur is V’sheevchacha, as you have pointed out, but the Vilna Gaon was of the opinion that the proprer pronunciation is Ooshvachacha, which has become more acceptable in many some Ashkenazic circles. The Sefer "Otzar HaTephilot" has a good basic discussion.