7E7 will cruise at approx M0.85 i.e. pretty much the same as most Boeings and as planned for the A380. Boeing had originally proposed building the "Sonic Cruiser" which would have cruised at about 0.95 but airlines said they wanted more economy not speed. Boeing has said that the technology proposed for the Sonic Cruiser when applied to a conventional cruise speed aircraft will reduce seat mile costs by about 20% when compared to B767-300ER and A330-200. It remains to be seen whether this wil be the case. Boeing are presently canvassing for launch orders for the 7E7 and it is likely that these will come from Japanese carriers. Formal launch targetted for mid this year with first deliveries in 2008 i.e. 2 years after the A380.
The "either A380 or B7E7" arguments are about as sensible as "either B747 or B767" would have been i.e. pointless - there's likely to be room for both types to sell in adequate numbers.