I saw the ps3 hack floating around that allows you to unlock the DLC characters, that's probably not a good topic for this forum BUT I took a look at the hack, which is nothing more than an edited INI file for the game, and learned a lot.
Here are my findings:
Motaro was either a planned character that was dropped or a character that they plan to add in the future via dlc. In the skeleton definitions section amoung expected entries like "human" and "shokahn"(four-arms) there is a "Centaur" entry. It is blank though, so he isn't in there.
Although we don't have a way to access them Kintaro, Goro and Sho Khan are setup as playable characters, not NPC characters. We don't have any way to access them via the player select menu, but they are setup that way. In the future I'm sure we'll see hacks of MK where these characters are playable. Or perhaps they are accessable via Kombat Kode?
Most of the oddball characters you fight in the challenge ladder are defined as NPC characters, BUT a few odd ones, like cyber reptile are setup as playable characters... they are simply commented out. Again, great potential for hacking.
The hidden characters in the arcade ladder are also setup as playable characters. For all but one I say "meh" but MK1 reptile was bad-ass. All of scorpion and sub-zero's moves made him the ultimate ninja.
The female ninjas either are going to have additional dlc costumes in the future or were planned to have additional costumes only they were dropped. According to speculation on the net, it was to be MK2 (not MK3) costumes but they were dropped. The actual ini file shows costumes as Character_A, Character_B, Character_C...ect... so it is unknown if this is true.
The ini file is setup in such a way that any kind of dlc content could be added, not just characters, costumes and fatalities. The only portion of the game that seemingly can't be added to is story mode (which makes sense).
As for secret finishers, babalities are it.... sorry.... All the animations are defined in the ini and aside from fatalities stage fatalities and babalities, nothing else is there.
The game is setup for special case flags. Most fatalities, for example have an alternate animation set for Sheeva defined (for obvious reasons...she is much taller and has four arms). Sonya's win animation has an alternate version for when she is indoors (planes can't fly inside!) This is good news! It means if a Odd-ball character like Motaro is ever added they have the ability to support fatalities on him.
A decent amount of avi files are in the game? I'm a bit confused by this as the story mode seems to use the in-game engine and the arcade ladder endings look like some form of flash.
The game was developed on a pc-version of the Unreal engine. The settings for starting the exe are still in the ini file. This means that there isn't a question if there is a pc port, the game was made on the pc (not uncommon) and if WB ever decided to release a pc port they could do it pretty much instantly.
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There are other things, but nothing interesting (at least to me).
I don't know if this is of interest to anyone, but it was to me, so I thought I would share. If people thought that sfiv was ripe for hacking they'll pass out once people start working on this one! You could literally build a character from scratch assuming the model format and animation format are figured out. Of course the real hacking can't begin until some dlc characters are released so we know what lines have to be modified to add a character to the select screen.