This is currently in Beta release, and you can sign up here.
XenConvert is the P2V and V2V tool for XenServer deployments.
The new version wil import VMware virtual machines in both VMDK and OVF packages, and is agnostic to the virtualisation product that generated them.
Although not mentioned, it is expected that this will be a FoC tool to entice end users to migrate from alternative virtualisation platforms since the announcement of their FoC XenServer product.