The next project, data modelling, warehouse, inventory?

So, as we are about to roll out a massive project to one of our clients, a 'very' large British company, I am excited in as much as there will be new things on the horizon. Several months ago now I blogged on an upcoming project involving workflow engines, and the fact that this was something about which I new absolutely nothing. Well I find myself in the same situation now.

It looks like for another client in the UK, a well known University, we have a need to develop some kind of inventory / stores / data warehouse system. Once again, I know nothing about this, and my first thought is, 'is there an excellent open source framework out there for this?'.

I am currently researching online, and looking through various books. But this sort of thing is of course better coming from those who are experienced, anyone out there know anything about this?

My last project hooked me up with the guys at JBoss, their workflow engine is really very good, and will only get better over time. What is out their for warehousing, inventory?

Any pointers appreciated :-)