She probably WILL be out in about 30 but not because she's a celebrity. Most people that get incarcerated (in my area, at least) end up serving about a third of their sentence. It just costs too much to house someone for a non-violent crime. She'll be out in a month, possibly be on some sort of probation/parole (even though violation of probation/parole is supposed to result in serving the whole sentence, it rarely does), and some sort of monthly fine.
I'm actually glad the judge layed down the law like she did. Too many instances where Ms. Lohan showed absolutely no respect for her situation. Not showing up for court, showing up for her court ordered classes, and continuously using intoxicants that she was ordered not to use could not be tolerated. Maybe when she get out, she'll be a better person.......and quite possibly, a lesbian.