Jeremiah mentions in his blog, the recent beta release of Amazon's EC2 (Electronic Compute Cloud) which I believe is one of a series of continuing significant releases. Amazon has started to leverage their infrastructure by offering it as a service with the S3 (Simple Storage Solution) and now with most recently with EC2.
This is significant because it introduces variable cost ways of what has traditionally been an expensive proposition. S3 provides the ability to store and transfer data at extremely cheap rates while EC2 enables organizations to create an 'instance' of their server and implement it in minutes.
A recently completed project required the upgrade of the primary web server (purchase new hardware, software, installation at the hosting facility, etc) as well as partnering with a Content Delivery Vendor. In a perfect world, utilizing the Amazon services could have saved us considerable hard costs and time. Of course any time you put 'beta' in front of a service, it is tough to endorse it as a primary solution since it will essentially negate an SLA. I look forward to considering the Amazon web services as a production solution when it is ready.
Yesterday, Yahoo released their Browser-Based Authentication which provides third-party web-apps the ability to leverage (with the user's permission) Yahoo user ids.
"You build great web applications. We have millions of users who store their data on Yahoo!. Browser-Based Authentication (BBAuth) makes it possible for your applications to use that data (with their permission).
BBAuth also offers a Single Sign-On (SSO) facility so that existing Yahoo! users can use your services without having to complete yet another registration process."

Wow. It is great to watch these integration points continue to open up whether it's Yahoo or Google. It's also interesting to consider why the adoption of web-based applications didn't succeed six years ago but now there is much wider acceptance. I'll save that for another post.
For more reading:
Jeff Bezos on Amazon's web services
Web Strategy by Jeremiah » Understanding Amazon’s EC3 (Cloud Computing)
Yahoo Browser-Based Authentication