One of the themes of Iwasawa Theory is to understand the structure of various naturally occurring finitely generated, torsion modules X over the formal power series ring Λ = Zp[[T1, ..., Tn]], where n ≥ 1. In particular, one can ask about the prime ideals of Λ which are annihilators of elements of X, the so-called associated prime ideals of X. For some interesting modules X, the associated prime ideals always have height 1. In contrast, for other interesting modules, it is conjectured that none of the associated prime ideals have height 1. In the latter case, X is said to be a pseudo-null Λ-module. In the former case, X has no nontrivial pseudo-null Λ-submodules. This talk will discuss various special cases illustrating those possibilities.