We will increase the number of Snapshots for 64bit mode to 10 this next release.

The total number of snapshots is dependent on the LVM, but 255 is a safe
number. There are, however, definite limitations as to the number of ACTIVE
snapshots:

32bit system:
- 10 per LV
- 20 per system

64bit system:
- 10 per LV
- 20 per system


http://kb.open-e.com/entry/2/