Technically it is required in California to have a front license plate, although I see many many cars without them. I have been running around without a front plate for a little over a year now. I'll take my chances, because a front plate would cover up most of my grille and affects cooling. Plus it looks tacky.
Most cops won't stop you just for a lack of a front plate, but you never know if they're having a slow day and might be looking to get somebody on a technicality.