According to this article it will use the same engine as Earthrise (a separate post-apocalyptic MMO--makes you wonder why they are giving themselves competition).
http://ve3d.ign.com/articles/news/45896/Fallout-Online-Project-V13-Details

Here are some earthrise screenshots
http://www.play-earthrise.com/gallery.php?type=1

I wonder if this means they met their funding threshold. I'd hope so, Interplay would look pretty silly announcing all of this now if they had a good chance of loosing the license in the near future.

Probably yes, given that their deadline is tomorrow.

Maybe interplay subscribes to the "cramming the night before" philosophy of production

Wow. That looks awesome.

This may be a "forget the game, sell the engine" kind of thing, ala Simultronics. Will be interesting to see what happens to Earthrise now.

If Earthrise is released well before the FO MMORPG this is actually a good move for them as it will lead to lots of free advertising.

Well, IPLAY did what they had to do: They brought in some professional help, with an established engine and folks who know how to use it.

So far so good.

aww, i like the idea of a fallout 3 mmo but like another engine is kind of unsettling man, i like the way FO3 looks atm and the way the physics are.

*Face Palm*

This MMO is by Interplay, the original creators of the Fallout series. Firstly, Fallout 3 is only by Bethesda, so there's a very small chance that Interplay would use their engine, and secondly, It would take rewriting nearly the entire engine to actually make it capable of being an MMO, if that's possible. Considering this engine being used seems to be optimised for Online, this makes much, much more sense.

It's not a Fallout 3 MMO, it's a Fallout MMO, developed partly by the original creators of the series.

That is correct. And because of this, I'd say it's unlikely that Interplay's Fallout MMO will have much to do with Bethesda's Fallout 3.

And in any case, as has been said, Fallout 3 is a single player game, so just directly converting the engine to an MMO would probably be rather difficult, using an engine that was designed to be used in an MMO makes much more sense.

Still, while we know what engine the game will use, this doesn't seem to tell us to much of what to expect the engine to be like, since beyond being a post apocalyptic game, the screenshots of Earthrise don't look too much like Fallout to me.

Considering that an Engine's influence on a game is kind of hard to judge based off of screenshots (there's some differences in how objects are rendered, etc - but beyond that it's primarily down to the art team as regards it's quality,) I'm not sure how big a step this is. Kind of interesting to see that they're moving forward with the project, at least.