The unique anykernel capability of NetBSD allows the creation of rump kernels, which are partially paravirtualized kernels running on top of a high-level hypervisor. This technology e.g. enables running the same file system driver in the monolithic kernel or as a microkernel style server in userspace. POSIX-compatible systems have been more or less supported as rump kernel hypervisors for the past 5 years. A long-time goal has been to extend hypervisor support further, for example to embedded systems. This would bring the solid driverbase of NetBSD available to such systems with only the cost of implementing the hypervisor.
The first release candidate of NetBSD 5.2 is now available for download at: http://ftp.NetBSD.org/pub/NetBSD/NetBSD-5.2_RC1/
NetBSD 5.2 is intended for those who have an application using NetBSD 5.0.x or 5.1.x who don't want the churn of upgrading to NetBSD 6.0, but would like bug fixes and some stable new features. There have been a number of changes since 5.1. See src/doc/CHANGES-5.2 for the full list.
Those of you who prefer to build from source can continue to follow the netbsd-5 branch, but the netbsd-5-2-RC1 tag is available as well.
Please help us test this and any upcoming release candidates as much as possible. Remember, any feedback is good feedback. We'd love to hear from you, whether you've got a complaint or a compliment.