Move-up/Repeat home buyer $6500 credit

[AZ-Tax]

From this website the following: http://www.federalhousingtaxcredit.com/faq2.php

"The Worker, Homeownership, and Business Assistance Act of 2009 has established a tax credit of up to $6,500 for qualified move-up/repeat home buyers (existing home owners) purchasing a principal residence after November 6, 2009 and on or before April 30, 2010 (or purchased by June 30, 2010 with a binding sales contract signed by April 30, 2010)"

Client just signed sales contract for a house to be built. Does my client have to close on their house by June 30th, 2010 in order to obtain the credit?

Can client claims credit on his 2009 tax return and if so what happens to the credit if their house does not close by June 30th, 2010?

[Bees Knees]

TTB, page 11-4:

Date of purchase. The first-time homebuyer credit applies to
individuals who purchase a principal residence in the U.S. after
April 8, 2008. The Worker, Homeownership, and Business Assistance
Act of 2009 extends the credit to apply to any taxpayer who
enters into a written binding contract before May 1, 2010 to purchase
a principal residence if the closing date on the purchase
occurs before July 1, 2010. Date of purchase is the date title closes.
If the taxpayer constructs the residence, the date of purchase is
the date the taxpayer first occupies the residence.

Election. For homes purchased after December 31, 2008, a taxpayer
may elect to treat the purchase as made on December 31
of the calendar year preceding the purchase. For example, a taxpayer
who purchases a home in 2010 may elect to claim the credit
on the 2009 tax return.