The CMS web page on PQRI says:
PQRI establishes a financial incentive for eligible professionals to participate in a voluntary quality reporting program. Eligible professionals who successfully report a designated set of quality measures on claims for dates of service from July 1 to December 31, 2007, may earn a bonus payment, subject to a cap, of 1.5% of total allowed charges for covered Medicare physician fee schedule services.
CMS recently issued an MLN Matters article on PQRI which is a useful resource for physicians and their staffs.