Asperger's Syndrome is an Autism Spectrum Disorder that is characterized by normal language and intelligence skills, but poor social skills. The DSM IV, published in 1994, has Asperger's Syndrome as a separate diagnosis that High Functioning Autism. The controversy surrounding AS comes from the research that has failed to find a difference between Asperger's and High Functioning Autism. This means that in the DSM V, which is to be released in 2013, AS will be added to the Autism Spectrum instead of being a separate diagnosis. Critics of this say that redefining AS would incorrectly label people with AS as having Autism. People with AS are different than people with regular Autism and therefore would be wrongly lumped into the label of Autism. Also, being able to diagnose a patient as having a specific disorder such as AS has been argued to help make more accurate diagnosis.
Since this topic can get a little dry, here's the South Park episode where they satire the Asperger's Syndrome debate: