Microsoft Excel 0-day Vulnerability FAQ document at SecuriTeam Blogs has been updated with information included to related Microsoft Security Advisory.
Updates included to Revision History too.

Additionally, my research say there was sample available as early as 12th June. TrendMicro TROJ_EMBED.AN write-up states 'Initial samples received on: Jun 12, 2006':
http://www.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=TROJ%5FEMBED%2EAN&VSect=Sn 
-> see Solution section

This Trojan was known as X97M_EMBED.AN before this week's rename process on Monday.
It is possible that other vendors had a sample more than a week ago as well, but there is no related field in their malware description documents. When checked it appears that Trend's HQ is located in Tokyo. I have no information where their laboratories are located.

Link to the FAQ document:
http://blogs.securiteam.com/?p=451 

- Juha-Matti