Note: this question originally asked about the suicide opcode, which has become selfdestruct in the meantime as per EIP6.
selfdestruct is the encouraged term and may be found in newer Solidity and Serpent code. It is the same API and behavior, as described in the other answers, and is an alias for suicide.
EIP6 describes the motivation:
The primary reason for us to change the term suicide is to show that people matter more than code and Ethereum is a mature enough of a project to recognize the need for a change. Suicide is a heavy subject and we should make every effort possible to not affect those in our development community who suffer from depression or who have recently lost someone to suicide.
