There are also papers on bounding the spectral properties of a regularised estimates of large covariance or inverse covariance matrices in the case of certain regularisation schemes. E.g.

Bickel & Levina: Regularized estimation of large covariance matrices. Annals of Statistics 2008.

Ming Yuan: High Dimensional Inverse Covariance Matrix Estimation via Linear Programming. JMLR 2010.

Paper that takes Raudys et's analysis further:

David C. Hoyle: Accuracy of Pseudo-Inverse Covariance Learning—A Random Matrix Theory Analysis. IEEE PAMI 2011.

There are also papers on bounding the spectral properties of a regularised estimate of large covariance or inverse covariance matrices in the case of certain regularisation schemes. E.g.

Bickel & Levina: Regularized estimation of large covariance matrices. Annals of Statistics 2008.

and many others focusing on sparse covariance estimates.