Some notes:
You may note that .52 is large then .51, this difference is that imanger is present where it is not in .051.
Imanger is the same as ibrowser, but there is image manipulation stuff present. Imanager is not fully working yet., as there is one bug in it where the image name is not yet passed back to tiny mce.
Another note: The CMS is not fully working yet, The sub parts such as article, faq, pages, and download are pretty much there. But the main manger is a in progress work, There is also some catalog display stuff for the CMS that that has been worked on.
Template stuff: there is a number of planned features in the design area that are kind of stubbed in in the menu. That is to say there are entries and a page to go to but they are not working yet. Once we get to beta level they will be.
Some work has been done on draft documentation, on how things work. Mostly new and change items in the cart is what has been targeted.
During the install there is a requirement for php 5.2.X, but the cat can run on php 4 at the moment. you can override this check by editing catalog/install/templates/pages/install_2.php around line 45. you can change the 5.2 to the version you are using. Once the classes get change to php 5 style classes you won't be able to run with php 4.
Tom