Capcom Unity has released a huge page with all you will ever need to know about Monster Hunter 3. This is just some of it.

Online / SpiltScreen

Online works pretty much like MH1 on PS2, It’ll be a Capcom Server with no Nintendo Friend codes. It’ll have a large town with many thing to do.

(arm wrestling mini game! among a few things)

Also can use Wii Speak to chat with friends or a Key Board. Also with Premade messages and emotes just like MH1, even few new ones.

Online Fee’s

Yup!  Its free!  No online fees for NA or EU!  Capcom heard your pleas and they listened.  They want Tri to be as much of a success as you do, and know that online fees would only serve to push awya potential customers.

Friend Codes

NO!!!  Thats right, no Wii Freind Codes, Its being Hosted by Capcom, and your chars will be stored on Capcom Server (you get 3 slots) You will be given a unique 6 digit Capcom ID.

Spilt Screen – can be played with friends at home!!! You can upload your chars to wii motes or use premade chars.  Players unlock monster thru offline game mode and has several arenas.

More info HERE