I have to agree with the commercialisation comment, especially as i have seen cards like 'happy fathers day from the cat'.
Mothering sunday (and yes i insist on calling it that and not mothers day) exists because of religious reasons, and i don't think this day should be undermined by other days, i mean come on now we have 'grandparents day'!!
I have not said anything to my dad because if i did i would get a lecture, but for all the other fathers who mark the day... have a good time
MB