Well looky here... Several Palm Pre accessories landed in BestBuy's system today. According to lgmack, it included 3 acrylic cases, a leather case, one case labeled 'palm pre case' and the "TouchStone Kit"(Charger with battery back cover). He mentioned that the Touchstone is listed at $69.99 which matches fits quite well with earlier reports. He also noted that though these accessories are listed as "In Stock Date: 5/10", he didn't find anything in the store yet.
What does this say about the Pre's release date? Not much, but soon. What I can tell you though is that the chances of a mid-May release is looking very dim right now. Your best bet would be on 6/7.
We'll be following this story very closely, so check back for possible updates.