Debuting with the Winter 2012 Steam Sale is something called "wishlist notifications" which appears to be:
We'll let you know by email or through our mobile app when the games on your Wishlist are on sale as a Daily Deal, Midweek Madness or Weekend Deal. Whether you're riding the bus, walking the dog, or stuck in a meeting, you'll know when there's a deal!
I haven't got a mobile device capable of using the Steam mobile app, so I'm limited to email-based notifications. How do I set up or configure email notifications for my wishlist items?
Best Answer
This setting is not at all clear, and rather heavily buried in their UI. First, start by clicking the account drop down in the upper right, and choose "Account Details" which takes you to:
Then, click the "Configure your email preferences" button. You'll end up here:
From here, you can opt to receive emails when items on your wishlist go on sale. I believe by default this is turned on. There aren't many configuration options, sadly...