VMware VM with more than 2TB of disk space

That's pretty much it in 4.x.

vSphere 5.0 allows for pass-thru RDMs to be larger (about 60 TB), but still has the 2 TB limit in place for VMDKs and non-pass-thru RDMs. (reference). Pass-thru (physical) RDMs and non-pass-thru (virtual) RDMs are distinguished by what degree the SCSI commands are virtualized by vSphere. Pass-thru RDMs are sent all SCSI commands with the exception of the REPORT_LUN directly whereas the the non-pass-thru RDMs have all their hardware characteristics hidden and VMKernel only passes the READ and WRITE commands to the device as it is presented to the guest operating system as any other VMDK on a VMFS volume (see KB2009226).

If you can upgrade to 5.0 and use RDMs, then great; otherwise, you're stuck gluing VMDKs or <2TB RDMs together in the guest OS with LVM or a software RAID.

Don't forget network attached storage type protocols (eg. NFS, CIFS). That is, if your SAN/NAS supports serves them up. Obviously a VM providing either of those would kinda defeat the purpose.

Linux guests can use multiple VMDKs for an LVM, which is not exactly spanning and not exactly RAID.