Hybrid Model – On Demand & On Premise….Where is the DATA?

Well atleast in today's Key note On Demand found a mention, but I had a question about the Hybrid model that SAP is discussing ..They do provide the option of having both on demand and on premise within a company/organization and indicated that they would work from on the same MASTER DATA / Data …Question : How are they going to manage/implement that???? Or Did I get it wrong??
Update: Peter Graf just confirmed that there is some form of data synchronization using the Enterprise Services…..Need to better understand this.
I find that blog very useful and even took some information for my own.
Best regards
Antoni Bielewicz
Computerworld Poland