i just upgraded to osx Lion this morning and i really love opening safari in full screen and swipe to go to other apps like Mail and iTunes by just swiping
then came to me the need to swipe between tabs
searched google and found this thread
the answer to this is very simple actually, since Lion already allow you to swipe between apps you can prefer not to use tabs instead just open a link in new window and swipe between windows
this may be not answering the question how to swipe between tabs but since Lion behave this way you can now just swipe between safari pages if you open them separately as new window (Cmd+click or Cmd+shift+click)