The Lakers are signing Brown to a 2-year, 4.2 million dollar deal. The way I see this is that the Lakers are basically buying time to decide who is going to take over as Fisher winds down the last year of his current contract. If Brown can continue to develop on the flashes of brilliance he showed in the playoffs, he could overtake Farmar for next-in-line. He's actually making more money than Farmar next year, which probably won't make Farmar, who is known for hiw confidence/cockiness, too happy.
Farmar has shown great potential as well, compensating for his size with grit, quickness, and decent outside shooting. His ball-handling is solid as well, but he has a long way to go to call himself the starting point guard of the Los Angeles Lakers.
The Lakers will develop both these guys in the triangle with Kobe/Pau/Bynum, then re-sign the one that they want after their respective contracts are up. They'll probably let the other one go to another team because they won't be able to pay the future market value for the fully developed guy they don't take, and won't really have to because they can sign someone cheaper (a veteran most likely), to come off the bench.
Ironically enough, Jackson doesn't like starting/using young point guards, so it should be interesting to see how this plays out along with Jackson's future with the Lakers. If he does come back for more than just next year, he might want a trade for another veteran PG unless Fisher can somehow still start in a few years, which I don't think he will be able to. That could be something Brown and Farmar should think about when they consider a future in LA.