Take a look at video of Scholastic's launch of "Potter Place" in New York. I wish I was there!
So that's how you pronounce Pensieve??? PON-siv, not PEN-seev.
Update: Bandersnatch has translated the Futhorc runes that run around the edge of the Pensieve in the video, and they say "Who will live and who will die?" and "There will soon be seven." We can't see the whole rim, but it seems that all seven of Scholastic's questions are represented in the design! Futhorc runes are the same ones that Tolkein used for the frontispieces and one of the maps he drew for The Hobbit and his Lord of the Rings books.
Update #2: I noticed in a video of Jo that she pronounced Pensieve PEN-siv. I have had the pleasure of hearing uber-Librarian Nancy Pearl talk several times, and one of the funny soliloquies she does is about how book readers often mis-pronounce things because we have only read them not heard them.