Re: VMware Snapshots? For real?
I do not know VMware Snapshots, but I'm assuming that they work like other snapshot systems.
Blockwise filesystem snapshots can have a place in regular backups, but only really if you limit the time you want to go back to the number of snapshots you keep. And this is determined by the amount of change in your systems and the amount of storage (usually disk) that you are prepared to keep back for the snapshots. In addition, they are probably useless for disaster recovery, unless you are maintaining cross-site snapshots (I don't actually know if you can do this, but I would guess that if you had cross-site mirroring, it would also be possible to keep snapshots on your other site).
If your backup requirements are longer term, or require recovery of individual files, then an agent based backup scheme is about the only way you can satisfy the requirements, IMO. This is especially true if you have a heterogeneous environment.
Of course if you are backing up the C: drive of all of your identical virtualised Windows boxes, then there are probably huge benefits in just backing up one copy of a de-duplicated, shared image at the de-dup'd level, rather than agent based backups of each system. But that is a particular system deployment method that does not match all requirements.