----
Not exactly, especially if you mean NeXT hardware.
You
could download the source to many GNUStep programs and build them with ProjectBuilder, but I think you might be limited to i386 hardware.
Running it on black hardware would probably have to be done on top of NetBSD (
http://www.netbsd.org/Ports/next68k/), but I don't think current GNUStep binaries (if any at all) have been built the NeXT68K series..
In theory, you could build GNUstep from source on NetBSD/next68K, however, if it was just as easy as 'configure, make, make install' someone would probably have done it by now.
You could have the STEP of your choice running in VMware or bochs or qemu on GNUstep on a modern machine, and to me, that would be the way to go.