As of Version 8.0, MultiPoissonDistribution has been renamed to MultivariatePoissonDistribution and is part of the built-in Mathematica kernel.
As of Version 8, MultivariateTDistribution is part of the built-in Mathematica kernel.
As of Version 8, NegativeMultinomialDistribution is part of the built-in Mathematica kernel.
As of Version 8, PrincipalComponents is part of the built-in Mathematica kernel.
As of Version 7.0, NonlinearRegress has been superseded by NonlinearModelFit and is part of the built-in Mathematica kernel.
As of Version 6.0, NotationBoxTag has been superseded by "NotationTemplateTag" and by ParsedBoxWrapper.
As of Version 6.0, NotationMadeBoxesTag has been superseded by "NotationMadeBoxesTag" and by ParsedBoxWrapper.
As of Version 6.0, NotationPatternTag has been superseded by "NotationPatternTag".