Wow! Ok now that you say that I see the same 16 second mask in the check stake code. Now this all makes sense in the context dooglus put it in. This is a pretty cool way to hash for proof of stake. Now I know why I was so lost :/
The nSearchInterval variable used to (before v2 of the protocol) be set to how many seconds since the last time we tried hashing, and the hashing function would then iterate through all those missed seconds.
In v2 we don't want it doing that, so we set the variable to 1 so we get a single iteration of the loop.
The 16 second mask thing makes it 16 times easier to find a block than it was before, since we get to try 16 times less often, but still want the same frequency of blocks being solved. This makes it 16 times more likely that two peers will find a block at the same time, and so we end up with 16 times as many orphans as before. Other than that it's cool though.
Oh, and as for SuperClam's "dooglus can verify and expound on this; but", I don't need to. She pretty much nailed it.