Fallout: New Vegas doesn't come out for around 6 more months, but that hasn't stopped people from pre-ordering it already. According to VGChartz, New Vegas has cracked the top 30 list for pre-orders at number 29 - right above Metro 2033. FONV currently has almost 19,000 units pre-ordered, and I'm sure will see that number steadily increase until release.
Check out the whole Top 30 chart here.
Thanks for the tip Dr.Xen!