Apple iPhone 3GS finally discontinued
GottaBeMobile

With the iPhone 5's release, the iPhone 3GS has been taken off the product lineup, and the iPhone 4 takes its place as the most affordable mobile phone offering now running iOS. Those who are looking to get an iPhone--at least in the US--can start from the iPhone 4 with 8GB storage for free on contract, and go as high as $399 for the just-announced iPhone 5 with a contract as well.

What Else You Need To Know

  • The iPhone 4 takes the iPhone 3GS's place as the most affordable iPhone in Apple's current lineup.

Other sources

The venerable 3GS was originally introduced way back on June 8th of 2009, making it the iPhone to have spent the longest time in Apple's product line. - Bryan Bishop, The Verge  
Other
iPhone 4S drops to $99, iPhone 4 now free; Apple discontinues the 3GS  

The venerable 3GS was originally introduced way back on June 8th of 2009, making it the iPhone to have spent the longest time in Apple's product line.

Phone Scoop
Apple Discontinues iPhone 3GS  

The iPhone 4S 16GB will be available for $99. The iPhone 5 will cost $199, $299, and $399 for the 16GB, 32GB, and 64GB versions.

GottaBeMobile
Apple Drops iPhone 3GS: iPhone 4 Now Free, iPhone 4S Now $99
iPhone Download Blog
16GB iPhone 4S now just $99, 8GB iPhone 4 is free, 3GS is a goner
The Inquirer
Apple says IOS 6 is coming to the Iphone 3GS, Iphone 4 and Iphone 4S next week
FSMdotCOM
Apple Drops iPhone 4S To $99, Makes iPhone 4 Free and Discontinues theĀ 3GS  

During today's keynote, Apple has announced the new prices for the rest of the iPhone line, killing the 3GS.