What is the penalty for not filing your 401k withdrawal the year after you took it out.
I closed mine out for 2,500 in 2007, then my husband closed his for $300 in 2008 and then this year we have 1 for $1500.

Normally 401k withdrawal is treated as income on your tax return. You also pay 10% penalty for early withdrawal. Use Form 5329, Additional Taxes on Other Qualified Plans (including IRA's), and Other Tax-Favored Accounts, to report any 401(k) tax penalty.
So you should report withdrawal in 2010 on 2010 tax return.

For 2007 and 2008, you can amend your tax return. You will pay tax due with interest and penalty. You can request for a waiver of penalty if you have a reason. Your U.S. Tax Return: Elective Deferrals 401(k) Plans (http://taxipay.blogspot.com/2008/08/elective-deferrals-401k-plans.html)