I have been waiting for this anouncment for a LONG time. Today Steam introduced their mobile app for iOS and Android. With the app you can chat with your steam friends and buy steam games. That means no missing out on sales because your away from your PC. We should be taking a closer look at the app here soon to see what else its capable of doing, stay tuned!
It should also be noted this is still in beta. The only way to sign up is to download and try to sign in. Some people will get to try it right away, others will have to wait a little longer