Stripe Checkout has been around since 2014, but along with the new page, there are a bunch of new updates today (coupons, tax rates, and more payment methods). More in the blogpost: https://stripe.com/blog/checkout.
Since January 2013 according to the Wayback Machine:
The blog post[1] (which seems like a better link than the landing page) says, "Today, we’re adding support for coupons, tax rates, and two new payment methods".