I did a quick look online to see who has it. GNU, DragonFly BSD, NetBSD, and FreeBSD all have a -delete option. OpenBSD seems to be the only one that doesn't (although its online manpage does give examples on how to do it with -exec and piping to xargs).
That's basically two flavours of UNIX (Linux and BSD), but that's OK - others are unfortunately either dead or dying. The UNIX family tree (http://www.levenez.com/unix) has been shrinking so rapidly in the last few years, that the current situation looks like the early years.
