Short answer: yes, schools take into account if your native language is not english. Tip: when writing your essays, get help from a professional consultant.

I do believe that your nationality/ethnic background count when applying to bschool. Fact is: if you're from an underrepresented minority/a really exotic location (i.e. Kenya or Bolivia), you stand a higher chance when applying because the adcom will go easy on you - the reason for this is that they need diversity in the classroom and you will certainly be a class "diversifier". However, note that if you are part of the overrepresented applicant pool, you might have to do stuff to distinguish yourself from the pack (i.e. if you're from the Indian IT Male group - even if India is "exotic" to me, there are a lot of people applying with this background)

I never knew that MIT -- Male Indian Techie group is so popular...

I'm not discussing popularity here, I'm just talking about the applicant pool. I have been browsing the Consultants section for quite some time now and I always see posts referring to this: every year, schools in the US receive a large number of applications from this demographic. Actually, I think ClearAdmit or Accepted.com (not sure which one) once did an article about this...

I completely agree with DanaJ. Additionally, you should know that international applications are down somewhat this year, so perhaps your timing will be better than in years past when there were record international applicants to US b-schools.