This is quite exciting! OpenMW is now looking to officially merge in the TES3MP multiplayer fork as an optional game feature.
Writing in a news post recently, the developers of OpenMW mentioned the TES3MP integration is likely to be done after the big 1.0 release they're currently working towards. Keeping that in mind, it may be quite a while before it's available. TES3MP has actually been an "official partner" of OpenMW for a while and so news about the project in future is likely to be more often and posted officially on the OpenMW website too.
The benefit isn't just that OpenMW will have easy to use multiplayer, as it will eventually have a "server side scripting system" too like TES3MP which should be interesting.
As for how OpenMW itself is doing, it's looking like the Shadows feature is finally going to be merged into the project. The 0.45 release should be a big one, with it currently in the release candidate stages.
See more on the official OpenMW website.
If you need a copy of Morrowind to use in OpenMW, you can find it on GOG.
It's a seriously impressive project, pretty amazing what they've been able to achieve. Hopefully we will eventually see projects like it for later games.