This is just a bugfix release. Someone noticed that zsync would be vulnerable to CAN-2005-2096, due to it's use of zlib code. So the patch for that is now done.
This release also includes some HTTP protocol fixes, as there have been some complaints/observations on how zsync failed to correctly implement some details from the standard. I still have some of these to do, and the fixes in this release have not been heavily tested yet, so let me know if there are any problems.
Get it from the download page.