Here is some of the small print from the bank promo page.
To be eligible for any of the cash bonus offers you must (i) open a new Comerica personal checking account, (ii) establish a qualifying product and/or service and (iii) register online for the program between the promotion period of April 26–June 30, 2010. Your participation will begin the first full calendar month after the promotional offer expires. Offer available to new checking account customers only. To receive the checking account bonus, you must open either a new Comerica Platinum CircleSM or Comerica Premier checking account AND make at least one deposit of $2,500 or more by August 31, 2010. Deposit must be new money not already on deposit with Comerica Bank. Platinum Circle customers must maintain a $50,000 average balance in combined consumer and/or business DDA, MMIA, CD or IRA account.
Visit the bank promo page to apply or for more information on this bank bonus