FYI to those of you using an Object Qualifier in your database:

There appears to be a problem with the DB creation scripts.  I'm fighting through it as we speak, but it appears that the {objectQualifier} is missing on many of the EventLog related table definitions.  Mostly in the CONSTRAINTS.  This may cause issues if you have an older version of DNN installed in the same database as this new version (as I do).

This problem may have been around for ages, not something new in DNN 4.5, but the net result is that you can't install 4.5 alongside another existing version of DNN.  Major headache for me...

The fix for the SQL scripts is relatively easy for 3.2.x  so multiple 3.2.x hosts can reside in a single DB...  3.37 and 4.x broke our application and ability to share a code base and single Sql DB so we forked the code at 3.2.x.  Our fork focuses on the concept of subportals and managed content applications.  aka. cafepress, communityzero, but combined.  We built our fork using the 3.2.2 core and modified a module developed by ezcam / tom mahoney / jerry spohn.

Our business case required more of the master of one than the jack of all trades approach.  Consequently we have taken the core and made modifications to the framework  and modules to deliver managed content applications to our clients.

One of our clients has an active site with 232,732 active portals each currently serving 27,918 active content pages for an e-commerce application.  Our fork of the code allows a single content portal to support skinnable subportals (Portal Alias in DNN terms but with limited admin) each of these portals are based on our managed content system but delivered under a unique brand, look and feel for each portal alias, each with their own seperate users and limited ability to customized the content and pages we authorize.

Whats different and nice about our approach is we maintain one main portal.  Each of the subportal owners receive our content and changes immediately and can control the presentation. Although we are a commercial enterprise we believe the DNN framework saved us millions of dollars in development allowing us to bring to market a solution in 1/24th of the time it would have taken  to complete from scratch.  We are currently revisiting the core at 4.5.x seeing if our fork can be reintegrated with the core. 

Initial indications do not look promising.  We are willing to share our code and case studies with interested members of the core team because se we believe the concept of subportals  to be integral, lacking and not even on the roadmap of  the DNN framework.

Not to hijack this thread, The answer is it can be done but you will need to modify  the core.