The corresponding packages are now available on Dotdeb for Debian 6.0 “Squeeze” on both amd64 and i386 architectures, with these changes :

APC has been upgraded to 3.1.14
Xcache has been upgraded to 3.0.1 (now compatible with Ioncube)
mysqlnd headers are now included in php5-dev to allow mysqlnd plugins to build

As usual, please read the ChangeLog before upgrading and be sure to use to the latest packages before reporting any issue.