ODFF (aka OpenFormula), the upcoming OpenDocument Format Formula specification, will require several changes to be implemented to the formula compiler and interpreter. Here we have schedules of features and changes done and planned. The schedule will be updated roughly every 2-4 weeks to reflect how things evolve.
All strings of new/changed function names and UI relevant changes like the functions' parameters in the formula wizard of course must be ready before each UI/feature freeze.
Items having the NewFunc flag are good opportunities for volunteers to jump on, since they usually don't depend on other changes and can be done within the formula interpreter plus surroundings.
The schedule reflects prioritized necessary changes, some of the new functions ODFF will define in the Large set were not scheduled for OOo3.0, but hopefully will make it into OOo3.1 and OOo3.2
You're more than welcome if you want to give a hand and help with implementation, of course not only for the functions that would otherwise be dropped, help is welcomed on any of the function items. Please join the Calc team on the dev@sc mailing list.
Note that several items have a reference issue assigned, many of them are also interoperability issues regarding compatibility with MS-Excel. So, while implementing the ODFF specification we'll increase interoperability at the same time, because when working on the ODFF specification the OASIS OpenDocument formula subcommittee tried to achieve compatibility where possible.