Recommended resources:
   Articles:
Alford, R.L., & Strother, J.B. (1990). Attitudes of native and nonnative speakers toward selected regional accents of U.S. English. TESOL Quarterly, 24: 479-495. Retrieved from http://jstor.org/stable/3587231

Cook, V. (1999). Going beyond the native speaker in language teaching. TESOL Quarterly, 33: 185-209. doi: 10.2307/3587717

Florence Ma, L. P. (2012). Advantages and disadvantages of native and nonnative English-speaking teachers: Student perceptions in Hong Kong. TESOL Quarterly, 46: 280-305. doi: 10.1002/tesq.2

Gluszek, A., & Dovidio, J. F. (2010). The way they speak: A social psychological perspective on the stigma of nonnative accents in communication. Personality and Social Psychology Review, 14: 214-237.

Ilieva, R. (2010). Non-native English speaking teachers' negotiations of program discourses in their construction of professional identities within a TESOL program. Canadian Modern Language Review, 66(3): 343-369. doi: 10.3138/cmlr.66.3.343

Moussu, L., & Llurda, E. (2008). Non-native English-speaking English language teachers: History and research. Language Teaching, 41(3): 315-348. doi: http://dx.doi.org/10.1017/S0261444808005028

Samimy, K., Kim, S., Ah Lee, J. & Kasai, M. (2011). A participative inquiry in a TESOL program: Development of three NNES graduate students' legitimate peripheral participation to fuller participation. The Modern Language Journal, 95: 558-574. doi: 10.1111/j.1540-4781.2011.01247.x

Shin, S. J. (2008). Preparing non-native English speaking ESL teachers. Teacher Development, 12(1): 57-65. doi: 10.1080/13664530701827749

White, L. & Genesee F. (1996). How native is near-native? The issue of ultimate attainment in adult second language acquisition. Second Language Research, 12(3): 233-265. doi: 10.1177/026765839601200301

I'll post some references for good books and dissertations on the topic soon.