Got a little code sample from a fellow watcher of Pashman's Goldmine (thanks Huseyin) on how to retreive the username of the current user via C# code. Since all code samples are useful, I've posted it below:
public void FormEvents_Loading(object sender, LoadingEventArgs e)
string xpath = "/my:oneriForm/my:nameTxt";
XPathNavigator field1 = MainDataSource.CreateNavigator().SelectSingleNode(xpath, NamespaceManager);
//string oldValue = field1.Value; // Read
string strUserName = System.Environment.UserName;
//userName1 = System.Environment.
In this case the user wanted the full user name too, and I advised him to try and replace the System.Environment.UserName with System.Environment.FriendlyName. I'll let you know if that worked.