Only if your employer provided with online access to tax documents. You need to contact the HR person and ask for a website URL, user ID and password.
The IRS doesn't provide online access to tax documents.
the best way - is to contact your employer and ask for a copy.
if you filed your 2008 tax return - your tax preparer may also have a copy of your W2 form.
Also if you files your tax return - the IRS may provide you a copy of the return or a transcript - but that will take some time.
Let me know if you need any help.