Spliting a string in plpgsql - Mailing list pgsql-general

Hi,
I'm writing a function in plpgsql and i need to do the following:

I have a string in the following format.

mail.yahoo.com

In this string, i need to figure out the number of dots in it and split the string into two
on last but one dot.

Is there any way to accomplish this.
Please let me know

Thanks
~Jas