When adding a collada file with transparent textures I have to view the object in transparent mode first in order to make it load (more or less) correctly. Before setting the model to transparent the textures are rendered incorrectly and transparency is ignored. After setting the model to transparent and back loading additional instances of the object show up correctly (when loading multiple instances and viewing one transparent it also makes the other one transparent however, this is probably related to
The model shows up as expected/desired transparency wise when viewing it in transparent mode (just the ordering of transparent parts is incorrect sometimes), but after disabling transparency mode it does not render the transparent parts of the texture correct anymore. My example object is a tree with different layers for leaves and the transparent parts of those layers often render all the way through to the floor or trunk ignoring other transparent parts behind them.
See this video for a better understanding (tree1 was exported using sketchup6 and tree2 using sketchup8): http://youtu.be/01VJa_z7SIY The model is available here: http://sketchup.google.com/3dwarehouse/details?mid=772012e0183084608da3b5c4427262d1&prevstart=0