Can an independent college student that is employed file his income tax after his mom whom already file and used him as her dependent because she financially sponsored his expenses?

Yes you can--and must if you meet the requirements--file even though your mom claimed you. You will not be able to claim your own personal exemption ($3650 for 2010) but will still get the standard deduction of $5700. If your income is below that amount you may still want to file to get a refund of any Federal or State tax withheld.