I have just updated the first preview of NetBSD-current release builds with ATF merged in to match the ATF 0.1 release published today. As already stated in the old news item: These will ease testing to the casual user who is interested in this project because he will not need to mess with patches to the NetBSD source tree nor rebuild a full release, which is a delicate and slow process. For the best experience, these releases are meant to be installed from scratch even though you can also do an upgrade of a current installation. They will give you a preview of how a NetBSD installation will look like once ATF is imported into it; we are not sure when that will happen, though.
By the way, ATF 0.1 is also in pkgsrc as devel/atf. This may be an easier way for you to try it, even though you will not get the NetBSD-specific tests.
For more details see my post to the NetBSD's current-users mailing list.