I also posted this in the Shadetree sticky, but here it is again.
Mods feel free to delete one of them if double posting this is not ok...
For the record, mine has not failed or cracked yet, but give it time...
So I was at the Toyota dealership today and checked out the tailgates.
They had about 30 tundras on the lot, 3 of which appear to be beefed up.
Yes, I looked at everyone of them.
So, it looks like Toyota is defiantly doing something about the weak corner issue.
I would expect that if anyone's fails, they are going to be replaced with one that has been welded in the right places sooner or later.
The welds shown are on both sides, there are also 2 more welds that are hidden, this was confirmed to me by someone who works at the IN manufacturing plant (who wished to remain anonymous).
The gate is substantially stronger.
On the gate with out the welds, I can flex the corner by pushing down hard with my hands, I can actually see it moving and beginning to split.
On the welded gate, I cannot get it to flex or move at all, even by standing on it and putting all my 220lbs on the corner, and bouncing.
Those that are worry warts, the fix is here and is spreading, don't lose faith in Toyota, they are fixing this and doing what's right.
Welded 
Welded 
UnWelded 