2) There are some mentions of new features in Beta 2 like:
- New XML-based file formats to make files smaller and more compatible ([1])
- Shared slide libraries stored on SharePoint servers ([20])
- Building block features to share design elements ([20])
3) But there is no definitive information on exactly when Beta 2 was released or details on all the new features it contained. Most of the articles are reviews and overviews rather than official release notes.
4) The best estimate for the release date of Beta 2 comes from the CNET article ([1]) which is dated May 23, 2006.
In summary, while the search results provide some useful context, there does not appear to be definitive information to directly answer the question asked about details on PowerPoint 2007 Beta 2 screenshots. The key facts are that it was likely released on May 23, 2006 based on the CNET article, and it contained a redesigned interface, new file formats, templates and animation features. But exact details are lacking.