Where can I find the list of new books/recent acquisitions by the Harvard Libraries?
There is no single new-title list for the Harvard Library, although several libraries do maintain local lists. For example, Tozzer Library lists selected new titles, (http://hcl.harvard.edu/libraries/tozzer/acquisitions/) as does Cabot Science Library (http://hcl.harvard.edu/libraries/cabot/acquisitions/). The Museum of Comparative Zoology (http://library.mcz.harvard.edu/newbooks/) also maintains a list. Please check the other Harvard libraries for local lists.
You can produce a quasi-new-book list through Hollis by choosing "Advanced Search," and searching by recent dates of publication. You can then narrow your results with the facets on the right of the screen. Of course, we acquire items retrospectively, and a search like that will not pick up older items we might have purchased recently, but it will provide a partial list of recent acquisitions.