Gwyneth defence is that she was referring to the Jay-Z & Kanye West song 'Niggas in Paris' though by including 'for real' after the title changes the song title into a statement, one of which contains a racially offensive word. While I don't think Paltrow is racist or intended to cause offence, she and everyone who chooses to defend her are missing the point.
The word 'nigga' is a derogation term for a black person and was used by whites during colonialism with the intent to degrade and ridicule the black man and woman. Recently the word has gained popularity in some black communities as is evident in hip-hop music, though while mainstream rap artists like Jay-Z and Kanye West are known to use the n-word in their lyrics, the word has not nor has it ever lost its racist connotations.
The use of the n-word is not openly accepted in black communities though some blacks that consume hip-hop music and its culture are more relaxed with the use of the word; hip-hop music and its culture is not synopsis with the vast and varied black cultures and communities of the world and therefore has no right to speak for or represent the black ethnicity as a whole.
This is why Gwyneth was wrong to use the n-word regardless who was or was not offended by it. Though interestingly Paltrow felt it appropriate to asterisk out the word but didn't consider that the word itself was simply too offensive to tweet. This highlights the urgency for hip-hop to retire using the n-word since it's blurring the true meaning/connotation of the word.
The commercialisation of hip-hop means that its audience has shifted from being majority black to a majority white or non-black audience making Gwyneth like many other non-black people fall into the trap set by hip-hop in using or relaying the n-word. The use of the n-word in mainstream hip-hop has come to imply to those outside of the black ethnicity that the word has been liberated and lost its original racist meaning, though this is not right; instead hip-hop decontextualises the n-word which is why some black people do not take offence of the word when generally said by another black person however when said by a person outside of the black ethnicity, specifically a white person, it puts the word right back into its original racist context.
The underlining message is that the n-word is still offensive and many black people still take offence in being called or referred to as the n-word. In Gwyneth's circle of black friends, whom I assume are the black celebrities defending her, may not take offence in her use of the n-word in their presents but her tweet was open to the public where this sort of language is inappropriate and should not be tolerated, this is the issue and this is why Gwyneth should be apologetic.
Other Article Links:
Ill doctrine why Gwyneth Paltrow should just say "Nuh" , newblackman.blogspot.co.uk
Gwyneth Paltrow 'niggas', and the black folks who cried wolf, clutchmagonline.com
Gwyneth Paltrow defends n-word tweet title song, omg.yahoo.com
Gwyneth Paltrow sort of uses the n-word on twitter but not really, observer.com