Meta keywords have no impact on ranking in Google whatsoever.
I have never heard of | as a separator though.
Usually it is comma (hard separator) or just leave spaces as separator. There is a post from tedster in this thread (from 2005!) discussing a difference between comma and spaces as a separator [webmasterworld.com...]
But as I said, I would not bother, Google said they have not been using them for a long time.
If you're going to use them, use a "," to separate them although I highly doubt the "|" will make any difference whatsoever. I couldn't agree more with BeeDeeDubbleU though. On a side note, I've eliminated the keyword tags on a site in an extremely competitive space and I've noticed no negative impact.