Xen & VxVM
The guys over at XenSource have pulled a master stoke, they have announced they will be integrating VxVM & VxFS into their Enterprise product. I'm a VMWARE VCP and it always amazed me that the VMWARE ESX didn't support fibre multipathing with load balancing. I've always taken multipathing for granted with Veritas (Symantec) VxVM DMP (a must with Photons) and latter MPXIO in Solaris.
I'm sure VMWARE will add EMC PowerPath soon to push along those CLARiiON.
Remember you can get Veritas Volume manager for free, check this blog post.