The biggest change is the support for higher resolution textures. This will take a lot of memory, tribes will easily use 800M on the computers that have been tested. Tribes should be able to grab up to 3.2G of memory now if needed so be aware of what your computer can do. PNGs are supported, and will be stored in memory as raw 24 bit bitmaps, but in order to make use of them you'll have to create tribes volume files with the pngs which requires a special switch "-nopbm", and renaming the PNGs. There are several other important conditions for textures as well. Terrain textures must all be the same dimensions, the mipmap creator for terrain will crash if terrain warping is enabled and this is not the case. Terrain warping can be disabled by printing $Terrain_NoWarping=True; to the console.
The method I used to create volume files with PNGs is as follows:
First get a list of every file in the volume file. this can be done from the command prompt by typing vtlist *.* Volume.vol > list.txt. This creates a list of every file in the volume in list.txt(and deletes any previous list.txt file contents so be careful). with this list I create a batch file to extract the contents of the volume by replacing the " " with "extract volumeName.vol ". this pulls all the files out of the volume and into whatever folder you are currently working in. I delete any bmps I want to replace, move the pngs to the folder and rename them all to bmp with rename *.png *.bmp from the command prompt. lastly I create another batch file from list.txt that replaces " " with "vt -nopbm volumeName.vol ". If you want to only replace some bmps make sure the original pbmps do not have this -nopbm switch or it will convert them in such a way that will probably not be desirable. the resulting batch file will make volumeName.vol with the specified contents, including the renamed PNGs.
Damage skins must be included with skins for objects that have them. they don't have to be similarly scaled up, but must be in the same format. so upgraded armor skins must include dskin1_armor.bmp and others as pngs.
A new variable $Interior::TextureScale has been introduced to deal with the limitations in how tribes handles interior textures. Rather than tracking each individual texture, I assume instead that they will all be scaled appropriately, so for a texture pack with 2048 textures, $Interior::TextureScale = 8.0; will display them correctly. This assumes that every 2048 texture was originally a 256 texture, and that any 128 textures are now 1024, 64 will now be 512, and so on. 2048 is the maximum texture dimension that can be currently supported. doubling that would probably require quadrupling the current memory that tribes can grab.