I doubt it.. they know the 720 (or whatever its name will be) will garner enough interest.
The videogame market is split in half and i guess it won't move much.. capabilities will be about the same and i don't believe MS will suffer any long lasting effects just because Sony went first in the announcement and that presentation was lukewarm at best, i.e. no real detail and merely a picture of the controller.
E3 will start the battle in earnest and i guess both companies will open up fully then. Until then everything that comes before are mere skirmishes.