The center of the sun is the hottest part (at around 15 million Kelvins, or 27 million degrees Fahrenheit). The temperature then drops to 5,800 K (10,000 degrees F) at the visible surface, although the corona (the part just above the surface, where solar flares are), can get much hotter (2 million K, or 3.6 million degrees F).
I found this information and tons of really neat stuff (pictures, movies, etc.) at http://sohowww.nascom.nasa.gov/ , which is the homepage for NASA's SOHO (SOlar and Heliospheric Observatory) project. For a good intro, click on "Classroom" (on the left hand side, under the "RESOURCES" heading), and then on the section for "The Sun 101" course.
Gregory Ogin, Physics Undergraduate Student, UST, St. Paul, MN
'We should take care not to make intellect our god; it has powerful muscles but no personality.'