AMD's Single Instruction Multiple Data (SIMD) instruction set, which has been known by the handle 3DNow! since 1998 is finally being put out to pasture.
The chipmaker has said that SIMD won't be supported by various processors currently planned. AMD's upcoming chips will support SSE (its many versions) so they probably will not miss SIMD which has largely been out evolved by SSE. In fact it is hard to find a developer who still thinks that it is important.
3DNow! functions still exist under the bonnet of PREFETCH and PREFETCHW instructions which are still going to be supported by new range of processors.