Here's a CentOS 4 VM with 4 snapshots, in each snapshot I added a 40M file and in two of the snapshots i snapped the memory as well.

Note a memory snapshot file is ALWAYS created if it doesn't contain anything !

The .VMSD contains the snapshot definition !

The .VMSN's contain snapshot of the memory !

The *-delta.VMDK's contain disk diffs !

http://farm3.static.flickr.com/2225/2065721033_1fae81b809.jpg

-rw\u2014\u2014- 1 root root 8.0G Nov 26 17:26 cent4-flat.vmdk
-rw\u2014\u2014- 1 root root 334 Nov 21 12:39 cent4.vmdk

-rw\u2014\u2014- 1 root root 1.4K Nov 26 17:31 cent4.vmsd

-rw\u2014\u2014- 1 root root 48M Nov 26 17:28 cent4-000001-delta.vmdk
-rw\u2014\u2014- 1 root root 219 Nov 26 17:27 cent4-000001.vmdk
-rw\u2014\u2014- 1 root root 18K Nov 26 17:27 cent4-Snapshot1.vmsn

-rw\u2014\u2014- 1 root root 48M Nov 26 17:29 cent4-000002-delta.vmdk
-rw\u2014\u2014- 1 root root 226 Nov 26 17:28 cent4-000002.vmdk
-rw\u2014\u2014- 1 root root 257M Nov 26 17:28 cent4-Snapshot2.vmsn

-rw\u2014\u2014- 1 root root 48M Nov 26 17:31 cent4-000003-delta.vmdk
-rw\u2014\u2014- 1 root root 226 Nov 26 17:29 cent4-000003.vmdk
-rw\u2014\u2014- 1 root root 257M Nov 26 17:29 cent4-Snapshot3.vmsn

-rw\u2014\u2014- 1 root root 16M Nov 26 17:31 cent4-000004-delta.vmdk
-rw\u2014\u2014- 1 root root 226 Nov 26 17:31 cent4-000004.vmdk
-rw\u2014\u2014- 1 root root 18K Nov 26 17:31 cent4-Snapshot4.vmsn