No. Satoshi is the minimum granularity (with the current blockchain format).
For further division, you'd either have to change the format and a majority of clients (basically, it would suffice if the 5 biggest mining pools made the change) or keep smaller amounts off-balance (i.e. outside the blockchain). That would mean additional bookkeeping, perhaps a system such as ripple could be used for this, but in general, it should be avoided. One of the elegant aspects of Bitcoin is that you can keep control over your funds yourself. Of course, with online wallets people already give up a bit of this essential ownership, maybe they would be ok with keeping sub-Satoshi balances in an external system as well and just hold their big savings within bitcoin.
Onkel Paul