Quoting from Double-Take Software's official announcement:
Double-Take Software today showed the continued success of its Double-Take for Virtual Systems product by announcing a complementary solution for joint Double-Take Software and VMware customers.
By using the two products simultaneously, customers achieve real-time data protection for virtual machines at an affordable cost. VMware products allow customers to build a flexible server infrastructure optimized for disaster recovery with the freedom to mix physical and consolidated virtual systems at primary and recovery sites. Double-Take Software solves disaster recovery challenges in this VMware environment by replicating business critical data offsite and providing failover capabilities.
Read the official announcement, here.