Announcement from Centers for Medicare and Medicaid Services (CMS):
"On April 15, 2010, President Obama signed into law the “Continuing Extension Act of 2010.” This law extends through May 31, 2010, the zero percent update to the Medicare Physician 
Fee Schedule (MPFS)  that was in effect for claims with dates of service January 1, 2010 through March 31, 2010.  The law is retroactive to April 1, 2010. 

 Consequently, effective immediately, claims with dates of service April 1 and later, which were being held by Medicare contractors, are being released for processing and payment.  Please keep in mind that the statutory payment floors still apply and, therefore, clean electronic claims cannot be paid before 14 calendar days after the date they are received by Medicare contractors (29 calendar days for clean paper claims)."
Given the uncertainty regarding MPFS claims with dates of service June 1, 2010, and later, stayed tuned for more info.