I'm puzzled by LR4 betas behaviour when entering custom cropping ratios. In LR3, I could just easily type in e.g. 55x33 and it would work. In beta, trying 55x33 .. and nothing happens. Using seems to work 5x3 works, but e.g. creating 940x198 banner graphics is beyond my skills with this beta version.
Looks like there is an issue with locales, at least on OS X Lion. I was running Finnish locale and it definately did not work (I tried it yet again).
Now, I set the locale set to "United States (computer)", and presto, entering 55x33 does work.
I suspect there's a bug with value formatting, since LR3 shows "940x198" and LR4 shows "9.4x1.98". I'd still prefer the LR3 way of showing the crop, since that's what I entered myself.