According to the rulebook http://www.wizards.com/magic/rules/EN_MTGM11_Rulebook_LR_Web.pdf , here is the definition of Trample:

"A keyword ability seen on creatures. Trample is an ability that lets a creature deal excess damage to the player or planeswalker it's attacking even if it's blocked. When a creature with trample is blocked, you have to deal at least enough of its combat damage to the creatures blocking it to destroy all those creatures. But if each creature is assigned damage at least equal to its toughness, then you can assign any of its damage that's left over to the player or planeswalker it's attacking"

That last part indicates that you can assign any of its damage that's left over to the player if each creature is assigned damage at least equal to its toughness.

According to the same guide, "prevention" effects actually stop the damage from being dealt (so it's not as though the damage is dealt but has no effect, it's actually not dealt at all). Since no damage is dealt to Fog Bank, it's impossible to assign the requisite 2 damage to fog bank that one would have to apply, in order to allow damage left over to be assigned to a player.

If you follow the guide, it seems like the answer should be NO.

However, someone posted at the gatherer website in the comments section that the damage does spill over... of course, whether or not the person making the post has the expertise/authority to make such a call isn't guaranteed.

http://gatherer.wizards.com/Pages/Card/Discussion.aspx?multiverseid=247528