Hey Nick,
Sorry, I got lost in the code..
I've since been going deep into phpschedule it. I've basically been adding a "Location" to all bookings. So a reservation will be made by a user of a resource and it will be utilised at a location.
Ex: John(user) will book the Garbage Cleanup Crew (resource) at the Rock Concert Site (location). I'm probably about 80% done.
As for what re-usable bits am i thinking; I'm not too sure at this point. Pieces I've modified that will be broken by upgrade include the additional translations, and a bunch of sql bits
lib/Database/Commands/Queries.php <--- get locations etc queries
lib/Database/Commands/Commands.php
lib/Database/Commands/ColumnNames.php <--- location column names
lib/Database/Commands/ParameterNames.php
also some cleaning up stuff could be done, like Namespaces, one class/interface per file...
It could be written as a ZF2 module and just use ZF's pieces like Views, Db_table adapters, ZendX_Jquery etc.
Would also love to see this hosted as a github project so others can freely contribute to it, fork etc...
Lots of thoughts, I know there isnt enough time in the day for even 1/2 of it.

Thanks for what you've written thus far.