At this moment, Adi Shamir is giving an invited talk at the Crypto 2008 conference about a new type of cryptanalytic attack called "cube attacks." He claims very broad applicability to block ciphers, stream ciphers, hash functions, etc.

My personal joke -- at least I hope it's a joke -- is that he's going to break every NIST hash submission without ever seeing any of them.

More later. (I'm sorry, but I missed the name of his student/co-author for this work.)

EDITED TO ADD (8/19): Okay, he thinks that AES is immune to this attack -- the degree of the algebraic polynomial is too high -- and all the blog ciphers we use have a higher degree. But, in general, anything that can be described with a low-degree polynomial equation is vulnerable: that's pretty much every LFSR scheme.