Someone put together a
Wikipedia article which goes over 'most everything you could want.
In summary, Caylee was a three year old girl who disappeared in June, and whose mom didn't report her missing until July. Mom's story has been comprised of half-truths and falsehoods, such as Caylee was dropped off with a sitter who had never met the family, at an address that hasn't been lived in for months... the works. It was also determined that a decomposing body had been in her car.
Incriminating web searches were done on the family computer (how to break a neck, how to make chloroform...), and Mom has been in and out of jail on this case. She was finally indicted for murder without a body being found, and now that a body has been found... may God rest Caylee Anthony's soul.