According to the IRS, excess deferrals should be returned to you if you notify the plan administrator before April 15th of the following year if your plan permits it. From what you have stated it appears your plan doesn't permit it but you should double check by reading the details of your plan regarding excess deferrals.

If after reading the section on excess deferrals, you notice a clause that the excess should be returned to you then notify the plan administrator about this.

If you are not able to get the excess returned then the IRS says the excess will be taxed twice. It is taxed when contributed ( you will have to report you excess on your 2010 taxes) and when it is distributed. If the entire excess is left in the plan then it may not be a qualified plan.

If you withdraw money before age 59.5 then you will be hit with the ten percent tax penalty. The best course of action is to read the details of the plan and bring it to the attention of the plan administrator. If there is a clause which permits you get a return on the excess and they don't allow it, you should notify the IRS about this. If there is no help there, you should bring it to the attention of a finance lawyer and have them send a letter to your plan administrator requesting a return of your excess.

Excess contributions to a retirement plan must be removed by the tax reurn due date plus profit or a 6% penalty will be assessed.