Of those sites that I follow in my RSS feed, the two that update the most, and seem to have the most active commenting groups, would be these:

1. Hemant Mehta's Friendly Atheist. True to his blog's name, he takes a softer approach than some (see below) in many respects, but still is no pushover.
2. PZ Myers's Pharyngula. If you don't mind the posts about squids, octopuses, and the like, you will not find anyone more outspoken and prolific as PZ.

From there, these guys will link to other atheist blogs frequently, so you can build your feed list that way.

I would suggest checking out the Atheist Nexus site? They also have news, are on Twitter and essentially keep a large group of international atheists in touch. :)

Without a doubt Twitter if you really want an up-to-the-second overview of atheist news. Search for #atheism #atheist and you will find lots of activity. I am @skrivener, and - not to promote myself - if you look I have a list with a few atheists, skeptics, scientists. Add the atheists, then look who they retweet and add them. I have wittled it down because there are some really active retweeters and it just gets too noisy for me, but if you're more into that than I am there are some REALLY active posters on Twitter.

Edit: although Twitter is definitely the place for up to the second information, here are some other resources.

Also worth being part of is Think|Atheist, which has many atheists, community groups, blogs, and so on. If something is happening in the American atheist world, then you're likely to see a post about it there, although it is not America-specific. It's an excellent place for meeting and discussing with others.

Richard Dawkins is arguably the best known English atheist, and his site is worth checking out, although it's not the best place for up to the second news.

Finally check out the atheist podcasts, such as Reasonable Doubts, The Good Atheist, The Atheist Experience/The Non-Prophets, and so on. Probably The Good Atheist is the best for staying current as they blog, and as Rob T mentioned blogs are a good source.

On that note, Rob T I think is the author of Science Based Parenting, which although not specificially atheist does bring up secular issues and is definitely worth checking out if you're a parent. Several other skeptical blogs and podcasts bring up atheist/secular/humanist issues frequently and are worth paying attention to, such as Phil Plait's Bad Astronomy.

Finally, if you set up alerts or just pay attention to Digg, then you'll see atheist news that's of strong note tends to float up there fairly quickly.

For atheist thoughts and news from Australia the best place to go would be to Sean the Blogonaut's site where he's started the Australian and New Zealand Atheist Blogroll (ANZAB) in the leadup to the Rise of Atheism Global Convention in Melbourne in March..