Should you still be scouring the 'net for another hands-on preview of Obsidian's Fallout: New Vegas, you'll find one more to scrutinize over at Game Revolution.
Returning to the Fallout game-scheme is the Reputation system found in the first two Fallout titles. Separate from and in addition to the Karma scheme utilized in Fallout 3, the Reputation system tracks a player's popularity, or lack thereof, with the various factions that play such a crucial role in the New Vegas iteration. The Brotherhood of Steel, the townships of Goodsprings and Novak, the New California Republic (back from the old games, its familiar-looking California State flag, now adorned with a mutant, two-headed bear, a nice touch) all these factions will come to have their own relationships with, and opinions of, players as they roam the Mohave Wastelands. And with little else in the way of readily-available distractions beyond scavenging food/ammo and taking regular Geiger-counter readings, news of the player's exploits travels fast.
Make the right friends or enemies, for that matter and you just might find yourself with some new dialogue choices with non-player characters that you didn't previously have access to. Stats and acquired skills can likewise influence the dialogue-options scheme; greater-than-average experience with, say, a particular type of weapon can cause dialogue options to splinter off in new directions, and yield new discussion-topics with NPCs who can accommodate you. In a world already blown to smithereens, who's going to trust a newbie with, for example, more high-yield explosives? If, on the other hand, you've already demonstrated some aptitude...