In one corner, we have CNBC's Jim Cramer. And in the other corner stands the heads of the four largest mobile operators in the United States: Ralph de la Vega (AT&T Mobility), Dan Mead (Verizon Wireless), Dan Hesse (Sprint) and Philipp Humm (T-Mobile). We fully expect Jim to lob a few hardball questions at these gentlemen, and there's no doubt zingers will be flung around. Who knows -- maybe we'll even get some news out of this keynote, so join us as we liveblog the Tuesday afternoon CTIA keynote, won't you? May 8, 2012 5:30 PM EDTLive from CTIA with Jim Cramer and the CEOs of the four largest US carri