I experience some issues when listing properties from childnodes. Here's an example:

    IPublishedContent testroot = Umbraco.TypedContent(999);
    var somechildren = testroot.Children;
    foreach(IPublishedContent child in somechildren)
    {    
         string myVal = child.GetPropertyValue<string>("myproperty");
         //Do some stuff with myVal     
    }

If I change the value of "myproperty"on some of the children, and publish that page. The old value still appears as "myVal". But, If I load every child again inside the loop, it works. Like this:

IPublishedContent testroot = Umbraco.TypedContent(999);
    var somechildren = testroot.Children;
    foreach(IPublishedContent child in somechildren)
    {
        var child2 = Umbraco.TypedContent(child.Id);
        string myVal = child2.GetPropertyValue<string>("myproperty");
    }