There is a link to the Dropbox downloads on our Steam Community Group page, or you can download and install the Desura client (unless you already have it), and go to Indiedb.com to install AfterMath via their service!
I will give warning that there are comments on AfterMath's Desura page regarding the AfterMath files being virused or trojanized (for lack of a better word), although I will assure you that there are absolutely no viruses whatsoever in the file. I will be looking into this though -- but it's nothing on Desura's side, which makes it confusing. So what you might be able to do is restore the file after your antivirus deletes it, and then see if it still acts up or whatever. Please contact me about any issues.
Anyhow, for the changelog (update history or update log, as I prefer to call it), it is available on Desura, or by going to Amupd8.tumblr.com.
Thanks for the support, and you will see the next update, prototype version 2.3 sometime soon!
JBJblaze and daelf3