Current OpenBSD is at 4.7 with a new release every six months.
diff below:
--- configure Mon Jun 8 17:22:57 2009
+++ configure.new Wed Feb 10 16:00:34 2010
@@ -2086,7 +2086,7 @@
# On OpenBSD, select(2) is not available if _XOPEN_SOURCE is defined,
# even though select is a POSIX function. Reported by J. Ribbens.
# Reconfirmed for OpenBSD 3.3 by Zachary Hamm, for 3.4 by Jason Ish.
- OpenBSD/2.* | OpenBSD/3.[0123456789] | OpenBSD/4.[0123])
+ OpenBSD/2.* | OpenBSD/3.* | OpenBSD/4.[01234567])
define_xopen_source=no
# OpenBSD undoes our definition of __BSD_VISIBLE if _XOPEN_SOURCE is
# also defined. This can be overridden by defining _BSD_SOURCE |