Why am I getting this make error w/ 0.4.0rc1 on Ubuntu
The first two lines are just warnings that can be ignored. But the error is a known issue caused by Bitcoin's use of a deprecated API that was removed in your version of Boost. The fix is to modify src/ui.cpp around line 1809 as follows:

  {
     if (!fAutoStart)
     {
-        unlink(GetAutostartFilePath().native_file_string().c_str());
+        unlink(GetAutostartFilePath().c_str());
     }
     else
     {


(Remove the line marked with a - and replace it with the line marked with a +.)