I finally figured it out. In what must be the next installment of increasing contextual controls in Yosemite, there now is a Downloads pulldown, a downward pointing arrow in the top right corner of the main iTunes window only visible after you click the 'Update All Apps' button when updates are available. This replaces the always present Downloads window option under iTunes’ Window menu, which sported a horizontal progress bar. Progress is now indicated by a tiny, fixed-size filling pie icon like that seen with podcasts etc. iTunes’ message bar now only flashes briefly with a new download; if you blink, you’ll miss it.
alternaut • moderator