My understanding (confirmed by several Indians) has always been that
Indian languages (that may be a bit vague) use the comma every two
digits, except for the thousands separator. This is illustrated in
the example from Tim, and also in the Hindi locale settings of
Windows XP
(if I could figure out how to do it I'd send a screen snap).
> days by Balaji Publications of Madras has
>
> lakh = 1,00,000 and
> crore = 1,00,00,000.
Richard Ishida