There are several Sigma lens instant rebates available in Canon, Nikon, Sony and Pentax mounts.  Savings appear to range from $50 to $200.  These instant rebates are set to expire July 31, 2012.

You can see all the lenses at B&H via the following links:

• Sigma lens rebates for Canon
• Sigma lens rebates for Nikon
• Sigma lens rebates for Sony
• Sigma lens rebates for Pentax