I'm special 
As a person who voted "special snowflake" the reason is:
As I will be converted the current campaign I run to 4E, and convert/recreate any rules that we use as custom now, and implement house rules in 4E as well, I reserve right to do the same for the races.
I DM a planescape campaign, but even there, some parts of cosmology I have adjusted. I like some of the ideas of the 4E cosmology but not all, so I will combine it with what I envision now, and just move stuff over.
My players will be a bigger issue, as currently, we have a:
Half Orc Barbarian
Dwarven Lycanthrope Fighter
Aasimar wildmage (specialist)
elven cleric
human swordsage
lillendi bard
halfling rogue/sorc
elven wizard
For some of the races/classes I'll already have to do some custom adjustments, and if anyone makes a tiefling, I use a planar table, for customized accents for the character (do you want a tail? horns? hooves? etc..make a customized tiefling) I envision that type of thing for the dragonborn...customize them a bit more..but that also depends on the feats they can take.
Ultimately, they sound more like a lizardmen with dragon blood, instead of a true half-dragon, so I may just leave it as such, so that players who choose to be an actual half-dragon have that advantage (breathe weapon from the start, etc)
I'll probably also change the tiefling back to having some type of planar heritage causing for their appearance/abilities.
Sanjay

As a person who voted "special snowflake" the reason is:
As I will be converted the current campaign I run to 4E, and convert/recreate any rules that we use as custom now, and implement house rules in 4E as well, I reserve right to do the same for the races.
I DM a planescape campaign, but even there, some parts of cosmology I have adjusted. I like some of the ideas of the 4E cosmology but not all, so I will combine it with what I envision now, and just move stuff over.
My players will be a bigger issue, as currently, we have a:
Half Orc Barbarian
Dwarven Lycanthrope Fighter
Aasimar wildmage (specialist)
elven cleric
human swordsage
lillendi bard
halfling rogue/sorc
elven wizard
For some of the races/classes I'll already have to do some custom adjustments, and if anyone makes a tiefling, I use a planar table, for customized accents for the character (do you want a tail? horns? hooves? etc..make a customized tiefling) I envision that type of thing for the dragonborn...customize them a bit more..but that also depends on the feats they can take.
Ultimately, they sound more like a lizardmen with dragon blood, instead of a true half-dragon, so I may just leave it as such, so that players who choose to be an actual half-dragon have that advantage (breathe weapon from the start, etc)
I'll probably also change the tiefling back to having some type of planar heritage causing for their appearance/abilities.
Sanjay