Yeah Soma, we know these things (no need to bold!)...that's why I wrote in my post above:
The problem is that your original question about what happens to sodium cannot be answered without considering what happens a short (very short) while *after* the signal has been sent.
I know the process as a whole is somewhat confusing, and I also know many Cell Bio texts (including the one that I read a few years ago) ONLY mention the sodium and calcium channels when talking about signal transduction and ignore discussion of the "cleanup" process involving the potassium and chlorine channels altogether (or they put the description of these channels in a completely different place)...my guess is this probably lies at the root of your original question about what happens to sodium after the action potential?
For a more complete view of the process that integrates the roles of the various channels into one discussion, I suggest having a look at the description given in the above mentioned "Lehningers Principles of Biochemistry" by Nelson, Cox (4th or I guess now 5th ed.) as it gives what I consider to be the most clear description of the interplay between all these channels that I have seen in a text (or at least it has a really good graphic of the ion channels, see Chapter 12).