Thanks to Kevin Cook's research, here is the first known poker dice patent:

http://patimg1.uspto.gov/.piw?docid=US000244520&SectionNum=1&IDKey=CCE6FAC5A439&HomeUrl=http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1%2526Sect2=HITOFF%2526p=1%2526u=%25252Fnetahtml%25252Fsearch-bool.html%2526r=1%2526f=G%2526l=50%2526d=PALL%2526S1=244520.WKU.%2526OS=PN/244520%2526RS=PN/244520

(after you get this page, click the links on the left to see the picture of the patent's poker dice.)

Note: not every browser shows it so well.

Here is my poker dice page, by the way:
http://www.antiquegamblingchips.com/pokerDice.htm

Here is a link to Kevin's dice club bulletin board:
http://groups.msn.com/DiceManiacsClubakaTheRandomFandom/messageboard.msnw

My poker dice auction:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3283105882&category=10909&sspagename=STRK%3AMESSE%3AIT&rd=1

Robert