renaming with number prefix

[Sven Guckes <guckes@xxxxxxxxxxxxxxxxx>]

Problem:
Rename all files within a directory such that their names
get a numeral prefix in the default sort order.

Example:

	$ ls
	abc bar baz foo zyxxy
	$ <command>
	$ ls
	1.abc 2.bar 3.baz 4.foo 5.zyxxy

So - what's that <command>?

Btw, "leading zeroes" would be a bonus.

Sven