This article talks about building a town as a point of light in 4E. It goes through the races in the PHB and no mention of half-orcs or regular orcs at all, so it doesn't look like we will see them except maybe in the MM.
http://www.wizards.com/default.asp?x=dnd/dudc/20071019
So seven races:
Human
Elf
Dwarf
Halfling (still using this name, how I hate this name)
Eladrin
Tiefling
Half-Elf (how I hate how this is a race and not just a feat for humans called "elf ancestry")
http://www.wizards.com/default.asp?x=dnd/dudc/20071019
So seven races:
Human
Elf
Dwarf
Halfling (still using this name, how I hate this name)
Eladrin
Tiefling
Half-Elf (how I hate how this is a race and not just a feat for humans called "elf ancestry")