Ahh Phishing, sounds like something you do on a boat with a few mates and beers but in the Steam world, it can create havoc for unsuspecting users.  The specific changes to the client include:

Steam Client

• Added contact email account verification by request and on new account creation
• Improved account security with verified contact email to prevent phishing
• Added mod support for Killing Floor
• Fixed memory leak
• Added 'officers-only chat' mode to group chats