I've used speedtree in the past, with some great results, not just trees, but mushrooms, and even a fleshly tenticle eyeball creature thing.

I'd love to update all the MW trees, keeping their original feel and textures (so texture replacers will work no problem) but I haven't the faintest idea how to get from Speedtree to NIF ensuring scale matches up too.

I've no real experience with 3D modelling software, so if I need something, some straightforward instructions would be great!

These two threads might help:
http://www.gamesas.com/bgsforums/index.php?showtopic=947079&hl=
http://www.gamesas.com/bgsforums/index.php?showtopic=938234&hl=

[Edit: link fix]

In my opinion i think billboard trees look terrible, no matter how well theyre made, they just ruin the look of everything

I haven't the faintest clue how to help you but speedtree done right looks excellent so I hope it goes well.

So anything ever come of this?

I thought Oblivion's trees looked pretty good....so I think I'll just agree to disagree there.

In case you are talking about that:

http://www.speedtree.com/

than a game engine should have a support of this toolkit: Gamebryo (Oblivion) supports it; older NetImmerse (Morrowind) does not. SpeedTree support is a "standard" for many modern games and engines.

In my tests billboards in MW for trees are OK only from a considerable distance. In general billboards in MW are fine only for something like streetlights.

I think Vality's trees look fantastic from any distance :shrug: It's just a matter of taste.

Indeed, I am curious myself as this would be a great mod by my book