Yes, I get 3 compiler warnings on linux. However, I would think that if *nix builds generated as many warnings as the x64 windows build, p5p would do something about it quicksmart.
Personally, I'm not greatly perturbed - the main problem on x64 windows is that, because there's so many warnings, your chances of spotting the odd one out that *does* have a bearing on a problem is greatly reduced.