red92, The original deadline was Nov. 30(before Dec. 1), but congress just decide to extended and expand the tax credit.
First-Time Homebuyer Credit
To answer the question, you can amend your 2008 tax return adding form 5405, which might get it to you sooner. But currently you can only do this if you close before Dec. 1., because the IRS hasn't update the forms yet.
Considering that the irs says to expect 8-12 weeks for processing an amended return, I would just file my taxes in February and get the refund in under 2 weeks. also I would change my withholding for December such that the IRS isn't taking anything out of my paycheck.(get some immediately and the bulk by the end of February)