I went to start my 2008 xD the other day and it really did not want to start. When I turned the key, the engine just kept turning but would not start. Being an ex mechanic of carburetor vehicles, I gave it some gas while trying to start, and it finally turned over.

When it finally started a puff of white smoke came out of the exhaust and I could smell gas pretty strong. Any theories as to what may have caused this would be greatly appreciated.

White smoke is usually gas. You need three things for combustion: air-gas-fire. Check your spark plugs, and see what they tell you.
http://www.superchargersonline.com/content.asp?ID=11
Or
http://www.superstreetonline.com/techarticles/130_0703_reading_spark_plugs/index.html

Any news on this? Has it happened again? That sounds to me like you flooded the engine -- the most common way is to start the car, move it a very short distance (back it out of the garage, or move it down the driveway), then shut it off, then repeat to move the car back into the garage and let your car sit overnight. In the morning ... yeah, it might not want to start.

If it's not a recurring problem I'd bet there's nothing wrong.

update?