What is happening immediately after conception?

Read more about the developing fetus where this came from... Pregnancy.org
And a great, short video of conception to birth can be found here.
Weeks one through four :

• Ovulation occurs - The time is right; now you just need this egg to be fertilized!
• Conception occurs - Did you know that during your pregnancy that your uterus will increase its capacity by 1000 times?!
• Gender is determined - Immediately upon fertilization your little one is set as a boy or a girl. Ladies, this is one that you can't take credit for since it is up to the sperm to determine the sex of your baby. Sperm carries either a "X" (girl) chromosome or a "Y" (boy) chromosome. (*Hint:* You will have to hold off on picking out the pink or blue until at least the second trimester when the gender will be visible via ultrasound.)
• Implantation - Some spotting (also known as implantation bleeding) may occur about 10 - 14 days after conception. You may believe you are starting your period but generally this bleeding is extremely light and lasts only a day or so.
• Neural tube forms - It will develop into the nervous system (Brain, spinal cord, hair, and skin). Already your baby has the foundation for thought, senses, feeling, and more!
• Heart and primitive circulatory system rapidly form - While still in its beginning stages, this is the very life support system that will carry your child throughout his or her life.