The latest updates of the CCRL Rating Lists and Statistics are available for viewing at:
http://www.computerchess.org.uk/ccrl/4040/ (40/40)
http://computerchess.org.uk/ccrl/404/ (40/4)
The live link to the 40/4 list given below is currently the most up to date for that list.

The lists sometimes get updated during the week and these updates can be viewed here:
http://www.computerchess.org.uk/ccrl/4040.live/ (40/40)
http://computerchess.org.uk/ccrl/404.live/ (40/4)
However, no game downloads are available from these live links.

The links to the various rating lists can be found just beneath the default Best Versions list.
For example there is a 32-bit Single CPU list.

Our 40 moves in 40 minutes repeating and 40 moves in 4 minutes repeating are both adjusted to the AMD64 X2 4600+ (2.4GHz).

Currently active testers are:
Graham Banks, Ray Banks, Shaun Brewer, Kirill Kryukov, Dom Leste, Tom Logan, Wassim Saeed, Andreas Schwartmann, Charles Smith, George Speight and Gabor Szots.
Currently inactive testers are:
Sarah Bird, Chris Taylor, Martin Thoresen and Chuck Wilson.

Be aware that in the early stages of testing, an engine's rating can often fluctuate a lot.
It is strongly advised to also look at the many other rating lists available in order to get a more accurate overall picture of an engine's rating relative to others.

40/40 NOTES

There are currently just under 150,000 games in the 40/40 database.

4CPU 64-bit Engines

Rybka 3 remains close to 150 elo clear at the top, ahead of both Naum 3.1 and Zappa Mexico II, which are very close in strength.
There is a 50+ elo gap back to Deep Shredder 11, Deep Sjeng 3.0, Toga II 1.4.1SE, Hiarcs 12 and Bright 0.4a (private). These engines have a small edge over Deep Fritz 10.1. We have not tested Deep Sjeng WC2008 in this category yet.
Glaurung 2.1, Loop M1-T,Thinker 5.2l Passive and Scorpio 2.0 are further back.

The relative ratings of the 2CPU engines that have been well tested are pretty much the same as their 4CPU counterparts.

Single CPU Engines

Rybka 3 is roughly 190 elo ahead of other engines in this category. Although more games are still needed, it seems apparent that the default settings are better than both the dynamic and human settings.
Naum 3.1, Zappa Mexico II and Fritz 11 are all pretty close in strength. It is expected that Deep Sjeng WC2008 will join them once we've tested it more extensively.
There is a small margin back to Shredder 11 and Toga II 1.4.1SE.
Hiarcs 12 is further back still, ahead of the group that includes Bright 0.4a (private), Fruit 2.3.1, Loop 13.6, Glaurung 2.1, Cyclone 1.0 and Thinker 5.1e Passive.

Free Single CPU Engines

Rybka 2.2 heads the field with a 50+ elo gap back to Toga II 1.4.1SE.
There is a similar gap back to Fruit 2.3.1, Glaurung 2.1, Cyclone 1.0 and Thinker 5.2e Passive. Spike 1.2 Turin and Bright 0.3a are a further 20+ elo behind.

CCRL tests a wide range of amateur engines (defined as free and having never gone commercial), ranging right down to the 1900 elo level. The intention is to get well over 200 games for each of these engines. We see it is a way of supporting and hopefully motivating these engine authors with their efforts.

Recently released engines that seem to have made good improvement are Twisted Logic, Cyrano, DanaSah, Rotor, Pupsi and NanoSzachy.

BLITZ NOTES

An enormous amount of work goes into the blitz list, and with over 350,000 games in the database, it is well worth a visit.

Of special interest to some will be the best free 1CPU engines list which is being constructed through a systematic testing approach as mentioned here:
http://kirill-kryukov.com/chess/discussion-board/viewtopic.php?f=7&t=3271

FRC NOTES

Ray tests only those engines that can play FRC through the Shredder Classic GUI.
If engine authors have a new and stable version of their engine that will run under this GUI, they should contact Ray if they wish to see it tested.

Rybka 3 has a massive 200 elo lead over the closely grouped Shredder 11, Naum 3.1 and Deep Sjeng 3.0.
Hiarcs Paderborn 2007 in fifth spot is well ahead of Fruit 051103 and Loop 10.32f (the most recent Loop version that could play FRC).

For FRC the best list to look at is the pure list.
http://www.computerchess.org.uk/ccrl/404FRC/

STATS/PRESENTATION NOTES

The LOS (likelihood of superiority) stats to the right hand side of each rating list tell you the likelihood in percentage terms of each engine being superior to the engine directly below them.

All games are available for download by engine, by month or by ECO code.
ELO ratings are now saved in all game databases for those engines that have 200 games or more.

Clicking on an engine name will give details as to opponents played plus homepage links where applicable.

Custom lists of engines can be selected for comparison.

An openings report page lists the number of games played by ECO codes with draw percentage and White win percentage. Clicking on a column heading will sort the list by that column.