Via the icedtea6-hg branch, you can now experience HotSpot 17 build 13:

$ hg clone http://icedtea.classpath.org/people/andrew/icedtea6-hg
$ cd icedtea6-hg
$ ./autogen.sh
$ cd ..
$ mkdir icedtea6-build
$ cd icedtea6-build
$ ../icedtea6-hg/configure --with-hotspot-build=hs17
$ make

and sometime later…

java version "1.6.0_18"
OpenJDK Runtime Environment (IcedTea6 1.9pre+r1f22e08af1f2) (Gentoo build 1.6.0_18-b18+r5b407bce9940)
OpenJDK 64-Bit Server VM (build 17.0-b13-rdd5a19d97c1d, mixed mode)