The Authors Guild has alerted its membership that S&S's new contract language would mean that the publisher would 'retain rights to a book for the entire length of copyright' (Milliot, PW, 5/17/2007)
Following on from this, the AG reports that S&S have backtracked slightly, accusing the AG of overreacting but also saying that the rights reversions issue will be looked at on a book-by-book basis.
Read your contracts carefully, talk to a contracts lawyer (or your agent) if you don't understand something and don't sign something if you don't understand what everything means or you're not happy with what's on the contract.
Thanks to Alison for the heads-up.
Also, for a different take, have a look at Juno Editor/ Paula Guran's blog entry on this.