THIS IS THE LINK TO THE FCC certification for the Nokia E90, that piece of paper being mentioned is not in that list, it might just be the confidential one, but the test report clearly says 2100 WCDMA...
nothing is confrimed yet, so you better hold on untill we get a more definite confirmation, but it is highly possible that this will be for the NA E90, that somebody hinted about...
edit this is interesting though, DL the pdf below and see page 7
https://gullfoss2.fcc.gov/prod/oet/forms/blobs/retrieve.cgi?attachment_id=746292&native_or_pdf=pdf