This Bloomberg piece on the state of the art market includes the following:
"Christie’s, along with Sotheby’s and Phillips de Pury & Co., abandoned guaranteeing minimum prices to sellers at the end of 2008. Many owners of high-value pieces, particularly contemporary works, turned to private transactions rather than risk high-value works at auction in a falling market. 'You will see guarantees coming back,' said [Christie's CEO Edward] Dolman. 'But it won’t be like the height of the market in 2007. We’ll be looking to share the risk much more. ...' Christie’s is currently discussing guarantees with certain sellers, Dolman said."