This seems to have become a "lost condiment" that many of us grew up with ... and you are not the first to have been looking for it, here or elsewhere. Vanwingen asked basically the same question recently in the thread Heinz Hamburger Relish- Is it still made?
Although the Heinz website still list it as a product
... apparently many people haven't seen it on their store shelves for some time - and have been looking for it. The folks at Hometown Favorites
have it listed as a product that they have confirmed
is no longer in production.
I must admit that I noticed it was no longer on the shelves 2-3 years ago ... don't know what made me wax nostalgic
and look for it after years of living without it ... probably about the time that I started looking for something another condiment gone the way of the dodo called "Brockles Sauce" (sp?) that I grew up with.