Daniel Grant had a story in yesterday's Wall Street Journal on "Secrets of the Auction Houses." He mentions at the very end that "a bill requiring auction houses to reveal their reserve prices is awaiting action in the [New York] State Legislature," but he doesn't discuss the (admittedly fairly toothless) auction house regulations that are already on the books in New York City. For one thing, if an auction house "has any interest, direct or indirect, in an article, including a guaranteed minimum, ... the fact such interest exists must be disclosed" in the auction catalogue or other printed material relating to the sale. (New York City Auction Regulations § 2-122(d).) The regulations do not, however, mandate disclosure of the precise nature or extent of the interest, including the amount of any guarantee.
The regulations also require that, if an auction house makes loans or advances to consignors, "this fact must be conspicuously disclosed in the auctioneer's catalogue or printed material." But this disclosure needn't be made on a lot-by-lot basis; it's enough for the auction house to include a general statement in the catalogue that it offers loans and/or advances to consignors. § 2-122(h). Similarly, section 2-122(f)(1) requires the auction house to disclose the fact that a sale is subject to a reserve -- but here again, this obligation can be satisfied by a general statement to that effect in the auction catalogue. The regulations also expressly permit the auctioneer to place so-called "chandelier" (or, as Grant calls them, "phantom") bids on behalf of the consignor up to the amount of the reserve (though this practice too must be disclosed in the auction catalogue). § 2-123(b). Once the bidding reaches the reserve, however, the auctioneer is prohibited from bidding any longer for itself or the consignor.
If you're interested, you should be able to find the regulations at this link. In the lefthand column, click on "Rules of the City of New York," then "Title 6 -- Department of Consumer Affairs," then "Chapter 2 -- Licenses," and finally "Subchapter M -- Auctioneers."
UPDATE: Felix Salmon finds the story "peculiar."