The coins first went on sale at the US Mint on May 5, 2008. All product options were suspended on June 30, 2008. As of today, they have disappeared from the US Mint’s Proof Platinum products page.
Here is a cached version of the US Mint Catalog’s page for American Eagle Platinum Proof Coins: Cached version. (Note: As of July 20, cached page has caught up with the live page, so the previous version is no longer visible.)
Here is the current version of the page: Live version.
When the 2008 Proof Platinum Eagles were suspended, the reason cited was the standard blurb regarding increasing precious metals prices:
Due to the increasing market value of platinum, the American Eagle Platinum Proof Coins are temporarily unavailable while pricing for these option can be adjusted; therefore, no orders can be taken at this time.
In past instances where products have been suspended, the US Mint has left product pages up and simply disabled ordering options. The 2008 Proof Platinum Eagles followed this same format until today.
There was also this unsubstantiated rumor posted on a forum:
There is speculation, and I stress it is just speculation, that proof platinum production is over for the year with mintages limited to the amount already ordered/minted/fulfilled.
I placed a call to the US Mint’s service number and was told that the product was suspended for repricing and no other information was available. Also, when a product is sold out, it is usually moved to the Mint’s No Longer Available page found here. As of the writing of this post, the 2008 Proof Platinum coins are not listed.
So where are the 2008-W Proof Platinum Eagles? Temporary website glitch, removed for repricing, or something more?
Incidentally, if it is a repricing, today’s spot platinum of $1,871 is below the spot price of platinum of $1,921 when the coins were first put on sale.