The Great Mausoleum, where Jackson lies, is an impressive structure; see photo at this link.
Michael Jackson will be in good company in the Great Mausoleum. Many great stars rest there, including Clark Gable, Jean Harlow, Carole Lombard and Red Skelton. The interior is a lot of marble -- to see what it looks like, view the private section where Clark Gable is located here.
Unfortunately for fans, Michael Jackson will be entombed in a private part of the mausoleum accessible only to family members; it requires a special "golden key of remembrance" to get in. This is wise, I think. Imagine what large crowds of fans and souvenir hunters would do to the quietude and solemnity of the place. However, this won't be a problem in a year or two. Time passes, passions subside and Michael Jackson will eventually be just one more famous name on the wall.
Other stars are buried in the grounds nearby -- James Stewart, Errol Flynn and Walt Disney, to name a few. To see a list of more, go here. To see a more complete, alphabetical list, see Findagrave.com, here.
Forest Lawn is not hospitable to star-gazing and refuses to give out information on the location of graves of famous people. The information, however, is readily available online and if you plan to visit, determine locations in advance. The guide at this link supplies a lot of information, not only for Forest Lawn but for various other cemeteries in and around Los Angeles.
Remember, however, that not all famous graves are accessible to the public. Some are located in locked sections or private gardens. Humphrey Bogart is one example.
A little known fact about Forest Lawn is that over 60,000 people have been married there, including Ronald Reagan (to Jane Wyman). There are several chapels on the grounds and they aren't limited to funerals.
My wife's cousin lives in Los Angeles and, until recently, worked at Forest Lawn selling cemetery plots. He found the work too melancholy for his tastes and left.
If you visit, be on your best behavior. A visitor's guide to Forest Lawn can be viewed at this link.
Update: See Findagrave.com for information and pictures of Michael Jackson at this link.