After investigating the missing Live Writers's spell checking problem for a while, I discovered that the problem was caused by my computer's regional settings (Greek). As it turns out, spell checking is only enabled when Live Writer is started using the en-US regional settings. The unfortunate assumption by the Live Writer's team was that since spell checking works only for English, it should be disabled for any other regional settings :-s ... If that assumption was correct, then other programs like Office for example shouldn't have spell checking either, for non English regional settings PCs.
Anyway, searching the web I found a patch you can apply that solves the problem (partially though). You can built a custom launcher that sets the CultureInfo object of a new Application Domain to en-US before launching live writer from it. You can do this like that:
static void Main(string[] args)
{
string path = Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles);
path += @"\\Windows Live Writer\\WindowsLiveWriter.exe";
AppDomain appDomain = AppDomain.CreateDomain("Live Launcher");
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
appDomain.ExecuteAssembly(path);
}
Unfortunately this solution does not work when you use the Blog this button from IE. So I'm still hoping for a patch from the developers team fixing this apparent problem.