Quoting from official announcement:
The Xen team are pleased to announce the release of Xen 2.0.5 !
This has a number of important fixes over 2.0.4, so we’d definitely recommend upgrading. Notable changes include:
* AGP support now enabled by default
* nasty save/restore/migrate problem in xend fixed
* memory ballooning with config highmem4g kernels now fixed
* nasty floating point issue fixed