The second DLC pack for Fallout 3 has been confirmed by Bethesda to be released in retail come August 25th, 2009. The said retail pack will feature Broken Steel and Point Lookout for both the Xbox 360 and PC.
To avail of this pack, you will need to shell out US 20. If you want to complete your Fallout 3 DLC collection, then you'll need another US 10 to pick up Mothership Zeta, the fifth and final piece of the DLC puzzle.
And then, on October, the Fallout 3 Game of the Year Edition carrying all five DLC packs will come out for the PS3, Xbox 360 and PC. Online retailers Amazon and GameStop both currently peg the bundle at US 59.99 for the consoles, and US 49.99 for the PC, to be shipped out on October 13th. But don't take this as final yet, because Bethesda themselves are not fully ready to disclose all pertinent details, so better take those price points and GoTY release date as tentative only.