What is R3 Hostkit ? Can I use it for interfacing it with .NET or Java?

It's been announced that R3 Hostkit is being available:

http://www.rebol.com/r3/docs/concepts/host-kit.html

but I don't even know what's it's about. Could RT communicate better to me and the outside world :)

So can someone explain to me what I can do with it ? For example can I use it for interfacing开发者_如何学C it with .NET or Java ? If yes how ?

Update: and now where can I download it concretely ? I just see (leightweight at least for me) doc but nothing to download :)

The R3 Host Kit is a DLL/shared library, which has a C-based API which allows you to evaluate Rebol expressions from within your own programs, and perform callbacks into that C code from Rebol.

In that sense you might compare it to something like what QtScript does for "JavaScript" (technically ECMAScript, but you know what I mean). Except the DLL is microscopic by comparison and does far more. A command-line Rebol interpreter is a fairly simple linkage against the Host Kit... while the R3 GUI clients are bigger codebases with more platform-specific code.

RebolTech is definitely not communicating what's going on with this well enough, because the big news is that they are open-sourcing the host kit and the layers above it. As I understand it, there's high odds the whole R3 GUI will be open-source. Here's the rather vague license they've got going:

For the source code, there will be two licenses. The first allows usage and reuse of the code as desired, with attribution and same license, even for usage outside of REBOL. The second allows usage, but restricts reuse only with the REBOL language from RT. In other words if MS wants to write R++, then they need to write their own code for some parts or contact RT for a special licence. Hey, RT's got to pay its bills somehow.

They say the precise official language of the licenses will be posted on www.rebol.com, but that hasn't happened yet.