When is a luxury rental apartment listing not a luxury rental apartment listing? Well, if you insist on getting technical about a rhetorical question, the answer is "never." But, for a new crop of Manhattan luxury rental listings, the answer is somewhat more complicated. Some of Manhattan's most impressive new luxury rental listings are either partnered with new construction luxury condos -- blockbuster midtown luxury rental The Ashley, for example, shares an amenity space, a developer, and a number of other commonalities with The Aldyn, a carbon-copy condo with which it was co-developed -- or, in such posh instances as Chelsea's promising Eventi rentals located on the upper floors of luxury hotels. For William Beaver House, a new luxury rental listing in the Financial District, the story is even more convoluted -- developed as a condominium, William Beaver House is still selling luxury condominiums. It just happens to offer some of the most luxurious rental listings in the Financial District, as well. And there is, of course, Frank Gehry's luxury rental at 8 Spruce Street in the Financial District, which ranks among the most luxurious luxury rentals in Manhattan real estate history. The phrase "condo-quality finishes" has never seemed more literally apt, and less like a real estate buzzword. While this new proliferation of condo-rental combos can make for some confusion when browsing Manhattan rental listings, one effect is clear -- it certainly has deepened Manhattan's already deep pool of high-end rental listings.