This is interesting for me because in general I'm a believer in allocating equities between US and foreign stocks according to their markets' capitalizations. Until now the simplest way of doing that was buying a total US fund (e.g. VTSMX) and a total ex-US fund (e.g. VGTSX) in roughly a 50/50 split. Now you can get the same effect with a single fund, and you don't have to worry about revisiting that 50/50 ratio over time.
In fact, I'm contemplating the following three-fund portfolio for my Roth IRA:
- Total World Stock Index, for 100% of equities
- Short Term Bond Index, for 50% of bonds
- TIPS fund, for 50% of bonds