The plain Geforce GT 650 TI has 128-bit memory and the faster memory interface definitely means the faster overall performance. It simply brings more bandwidth.
We don’t know the clock but the GT 655 name sounds very plausible. The chip behind the card is most likely the GK106, but this is also something that we need to confirm.
The card should be coming very soon and it sounds like Nvidia thinks that there enough of a gap between Geforce GT 650 TI and Geforce GT 660 to fill with a new SKU.