United States v. Walker, Docket No. 05-3851-cr (2d Cir. March 30, 2006) (found here)
Walker appealed his 15 year mandatory minimum sentence under the ACCA arising from his three prior violent felony convictions -- including New York State convictions for robbery in the second degree, robbery in the first degree and attempted assault in the second degree. (Walker was convicted in federal court of being a felon in possession of a weapon.) Specifically, Walker argued (among other things) that his New York State conviction for attempted assault in the second degree should not count towards the three prior convictions that qualified him for the mandatory minimum 15 year term of imprisonment under the ACCA because "New York's own definition of 'violent felony' for purposes of its sentencing laws does not include attempted assault in the second degree." The Second Circuit rejected Walker's argument and affirmed his sentence.
This seems like the right result. Congress is free to define "violent felony" in any way that it desires, regardless of how state law views the same conduct.