The Topalov - Kramnik World Championship unification match begins Saturday, September 23 at 7:00 a.m. EDT (3:00 p.m. Kalmykia time). There are several sources for live coverage and a few places you are likely to find breaking news and annotated games. Here is my viewer's guide, which I may need to update once the match begins.
Topalov - Kramnik Match: World Championship 2006
You can see the live feed without commentary from the official site for free.
Susan Polgar Chess Blog by GM Susan Polgar
Susan Polgar is giving near-live commentary at her blog, while following the ICC webcast. Because this link has gotten popular, it can take a while to load.
FICS: Free Internet Chess Server
Free registration, for free online play and free live broadcast of the World Championship. Yeah, it's really free -- sort of like ICC used to be.
ICC: The Internet Chess Club
ICC offers a seven day free trial. Membership costs $59.95 per year or six months for $34.95. I originally joined ICC during the 2005 FIDE Championship in San Luis and have to say that their coverage of that event alone was worth the price of membership. ICC also offers other premium services, including rated online play and lectures and radio broadcasts from Chess.FM with live analysis by GM Dzindzichashvili.
You can get a 30-day free trial membership, or buy Fritz from ChessBase to get a bonus year membership. Membership is 29 Euros (the Playchess server is especially popular in Europe). They offer live coverage of the games with GM commentary by Yasser Seirawan.
Kramnik - Topalov World Championship Match from Chessgames.com Chessgames.com will provide live coverage to premium subscribers ($25 per year) but will also offer free links on their page for those who would otherwise be in the dark. Observers can comment in a running bulletin board thread.
World Chess Network
WCN will offer live coverage and professional commentary. Memberships range from $1.95 per month (or $19.95 per year) for Silver to $4.95 per month (or $49.95 per year) for Gold Membership. You can join for free and play live unrated games with occasional "Gold for a Day" promotions (which may or may not be available during the Championship).
Promises "live GM's annotations of the games," but I do not see them delivering.
Topalov - Kramnik Match: World Championship 2006 News and FIDE's Main Page from FIDE
The main FIDE page offers news coverage and live games.
ChessBase News will offer excellent coverage of the event and already has a good story (complete with a schedule and useful links). Annotated games by Mihail Marin, who is the best annotator around.
TWIC: The Week in Chess
Often offers commented games (with comments by Mark Crowther and notes by IM Malcolm Pein) and always has the PGN very quickly. They may also have a new look some time during the championship.
You can always search the latest news about the match through Google.
The following sites often feature annotated games. They are listed in order of frequency of publication (though some may publish more frequently for this special event).
ChessBase News with annotations by Mihail Marin
TWIC: The Week in Chess with comments by Mark Crowther and notes by IM Malcolm Pein.
The Chess Mind blog by Dennis Monokroussos
One of the fastest annotators of the games.
The New York Times by Dylan Loeb McClain
There is excellent next-day coverage of the match, complete with annotated games and a report from Elista. But you need to register to read today's paper and past editions are for sale only.
Chess Pro with annotations from GM Sergey Shipov and Maxim Notkin
e3 e5 with annotations last year by K. Sakaev and V. Yemelin
Inforchess with annotations by IM Hector Leyva (and others)
An excellent Spanish-language site with annotated games and reports after each round, often a day later.
Blog commentary on the games.
An Italian-language blog with excellent commentary.
The Daily Dirt Chess Blog by Mig Greengard
Chatty kibitzing and useful links to other commentary.
Susan Polgar Chess Blog by GM Susan Polgar
The Closet Grandmaster from Australia
TCG is a frequent blogger who covered the 2005 FIDE tournament very well.
Chess News and Events by Goran Urosevic
A blog that features frequent news updates and useful links, from the webmaster for World Chess Network.
Chess Piece by Bobby Ang at IndoChess
Daily Telegraph with Malcolm Pein
Washington Post Chess column by Ljubomir Kavalek (usually Mondays)
LA Times chess column by Jack Peters (usually Sundays)
British Chess Magazine, news editor John Saunders
One annotated game from GM Susan Polgar so far, but it was difficult to find and not advertised on their main page, so I have no clue what's going on.
Video lectures for subscribers, with notes to the World Championship games soon after they are played. This looks like a very well run organization, but I have not yet tried subscribing myself.
Chess Today (subscription)
The daily chess newspaper offers analysis if you subscribe.
I will add any others I come across or which readers recommend. I also welcome corrections or additions to the information posted here.