Microsoft has released a public beta of the next version of Internet Explorer. According to a comment on the IEBlog, this beta release is only available for users running Windows XP SP2 on a 32-bit system. x64 and Server 2003 builds are expected at a later date.
For anyone interested in installing IE7B2, I’d highly suggest that you take a look at the release notes, IE7 Newsgroup, and the IEBlog first.