I thought I'd do a little analysis of the new scripting functions.
DismountObject
MountObject
For the horse lovers out there, this is a very good sign. My guess is that while we won't see official horses for the first release, there's still the "guts" of the system in place. I'd expect mounts in an expansion for sure, and perhaps even in an unofficial hak.

CloseGUIScreen
DisplayGUIScreen
DisplayInputBox
DisplayMessageBox
SetGUIObjectDisabled
SetGUIObjectHidden
SetGUIObjectText
SetLocalGUIVariable
This seems to be the new GUI functions. It looks like there's a simple input box (e.g. for naming a custom item), a pop-up message box, and the more complex custom GUIs. I especially like how you can set local GUI variables and text, allowing for things on the GUI to change. I'm guessing the ability to disable or hide GUI Objects lets you enable/disable buttons and the like.

GetGlobalBool
GetGlobalFloat
GetGlobalInt
GetGlobalString
LoadGlobalVariables
SaveGlobalVariables
We've heard hints of global functions. I'm fuzzy on what they're used for and how they're different than the database functions.

DespawnRosterMember
GetFirstRosterMember
GetIsRosterMember
GetIsRosterMemberAvailable
GetIsRosterMemberCampaignNPC
GetIsRosterMemberSelectable
GetNextRosterMember
GetObjectFromRosterName
GetRosterNameFromObject
GetRosterNPCPartyLimit
RemoveRosterMember
RemoveRosterMemberFromParty
?SetIsRosterMemberCampaignNPC
SetIsRosterMemberSelectable
SpawnRosterMember
It seems there's a thing called a "Roster", though I'm not sure what it is, exactly. Maybe it's a way of associating NPCs with a player? Maybe it's part of the stronghold system?

EffectAbsorbDamage
EffectArmorCheckPenaltyIncrease
?EffectAssayResistance
EffectBardSongSinging
?EffectBonu***points
EffectBreakEnchantment
EffectDamageOverTime
EffectDetectUndead
EffectHealOnZeroHP
?EffectHideousBlow
?EffectJarring
EffectLowLightVision
EffectMaxDamage
EffectMesmerize
EffectNWN2ParticleEffect
EffectNWN2ParticleEffectFile
EffectNWN2SpecialEffectFile
EffectOnDispel
?EffectSeeTrueHPs
?EffectSetScale
EffectShareDamage
There's lots of new effects, many of which are likely for the new spell functions. The NWN2 particle effect ones are especially neat. I'm guessing you make a "particle effect file" via the plug-in, include it in the module, and then call it with this script. Snazzy.

GetCanTalkToNonPlayerOwnedCreature
SetCanTalkToNonPlayerOwnedCreature
It sounds like NPCs have a flag that let you make sure only the player can talk to them.

GetControlledCharacter
?SetOwnersControlledCompanion
This forces the player to control a companion, which is amazingly cool. You could almost mimic some of the DM client functions by using a normal PC, adding a creature as a companion, and then controlling it. There's a few other related "Ownership" scripts.

PlayCutstomAnimation
If this is what I think it is, it could be the coolest thing since sliced bread. Adding custom animations to NWN was very difficult, and this single function might help get around that huge limitation.

SetCombatOverrides
ClearCombatOverrides
This might be an easy way to fiddle with a creature's AI, especially mid-combat.

GetEventHandler
SetEventHandler
SetCreatureScriptsToSet
I think these let you change the scripts for a creature dynamically. Pretty handy.

SetDescription
People have wanted this for a long, long time.

There's still some mystery functions. I don't get the Set/GetBumpState, SetScriptHidden, and IsInMultiplayerConversation. There's also some more that have a pretty obvious function (e.g. GetAge).

All-in-all, I'm pretty excited about all these new functions we can play with. Great stuff!