UPDATE (15 September 2008): per Adam Machanic's comment, this syntax is in fact deprecated in compatibility mode 9.0 databases (e.g. SQL Server 2005). Thanks, Adam!
I learned something interesting recently (well, not too recently; I'll be going through my inbox in the next week or so catching up on blog-compatible content) which seems worthy of sharing.
There's been a lot of talk about the deprecation of "old style" (ANSI-92) JOIN syntax in SQL Server 2008. Consider the following old-style LEFT OUTER JOIN:
SELECT tableA.id, tableB.id
FROM tableA, tableB
WHERE tableA.id *= tableB.id
The table citation portion of the query (FROM tableA, tableB) is ANSI standard and is NOT being deprecated. The LEFT OUTER JOIN syntax (*=) is not ANSI standard and IS deprecated as of SQL Server 2005.
So my old friend Brian can keep separating his tables with commas just as he's been doing.. but if he wants to do a LEFT or RIGHT OUTER JOIN, he'll need to use the "new" syntax.
Thanks to the always-knowledgeable Umachandar Jayachandran for sharing this information.