I’ve heard N.T. Wright suggest on more than one occasion that Paul is doing a play on words in Romans 2:29 when he says “…a person is a Jew who is one inwardly, and real circumcision is a matter of the heart—it is spiritual and not literal. Such a person receives praise not from others but from God.” This is suggested because “praise” (Gk. ὁ ἔπαινος) is meant to drawl the hearer’s attention (at least some of them) to name from which Jews derive their identity, the tribe of Judah (יהודה), which means “praise.” In other words, one who is a “Jew” (those who praise) receives his/her praise from God, not other people.
I found a footnote from Leon Morris that states the position more fully. [1]
Käsemann’s point that the Roman audience wouldn’t have understood Paul’s play on words is a valid criticism, but Paul may not have cared if everyone understood him. He may have wanted a few of his fellow Jews to understand his message.
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[1] Leon Morris, The Epistle to the Romans (PNTC; Grand Rapids: Eerdmans, 1988), 142. Fn. 168. Screen shots from Google Books.
the archives near Emmaus 
Käsemann’s point that the Roman audience wouldn’t have understood Paul’s play on words isn’t true if the Roman audience were Jews of the House of Judah, or even other Israelites familiar with the meaning of names in Israelite genealogy.
Käsemann is assuming Paul’s Roman audience were Gentiles (so non-Israelites according to common presuppositions). This presupposition is unwarrant, so there is room for Käsemann to be wrong.
Incidentally, this isn’t some diatribe on Paul’s part de-franchising Judah as the ruling tribe, or Israel as the Kingdom of God, because it’s showing that faithfulness to the covenant (a spiritual thing) is the determining factor of what constitutes a right relationship with God. The New Covenant established in Christ reaffirms this right relationship [Jer 31:31] however we see from Paul’s argument in [Rom 9:13] that this election is easily lost by a simple rejection of God.
Both Esau and Jacob inherited (by blood) the promises of the covenant [Heb 11:20] however Esau’s ungodliness excluded him [Heb 12:16].
Good points… interesting word play. I think it’s reasonable to expect such things from Paul considering that he uses similar word play elsewhere in the scriptures.