Pokemon.com has stated that in effect from September 1st 2010, the new Modified Format banlist is to take effect;

Only cards from the following setlists will be allowed for use in competitively play:

• Majestic Dawn
• Legends Awakened
• Stormfront
• Platinum
• Rising Rivals
• Supreme Victors
• Arceus
• HeartGold & SoulSilver
• HS - Unleashed
• Pokemon Rumble
• HS Trainer Kit
• Promos DP22 and higher
• Promos HGSS01 and higher

Redshark will likely update its banlists soon as well, but I suggest we all get ready and start learning to live without Cloydal, Togekiss, Gardevoir and Felicity.

Pokemon:
Secret Wonders:
Flygon (F)
Gardevoir
Gardevoir Lv. X

Great Encounters:
Claydol
Darkrai
Darkrai Lv. X
Cresselia Lv. X
Lapras
Togekiss


Trainers:
Amulet Coin
Felicity's Drawing
Lake Boundary
Leftovers
Moonlight Stadium
Professor Rowan
Rival
Team Galactic's Mars
Team Galactic's Wager
Time-Space Distortion

Energy:
Multi Energy

Dusknoir DP,
Alakazam MT
Azelf MT
Lumineon MT (a personal favourite :( )
ROSANNE'S RESEARCH
Mew SW
Unown G
Pachirisu GE

NIGHT MAINTENANCE!!!!

Roseanne's Research and Night MAintenance were both in promo packs, so they're safe.

Zone and Zone Lv. X Gone too.

Guess we'll be using Metagross (ewwwww) for free retreat bodies now.

SDS, none of the POP sets are legal come September. Read the list of sets that are legal come September, they are not mentioned at all.

Deck, Flygon (c) is still legal and still has the best free retreat body in the game. Flygon Lv. X is also still awesome to bitch-slap other Lv. X users.

My bad SDS. In any event for the time being it looks like Staraptor FB Lv.X is the most likely candidate to fill the void left by Claydol. None of the cards in the Japanese set have drawing Poke-Powers remotely comparable to Claydol GE's. Porygon2 GE has also been cycled out. Either that or you'll need some good deck specific starters.

Right now Jirachi + Staraptor FB Lv. X seems like the best way to get a consistently good start.

Loss of Moonlight Stadium deals a huge blow to a lot of Psychic and Dark decks. No more free retreat for Sableye...

The most likely void to fill Claydol is Uxie X. Easier to pull and the basic is actually useful!

Magnezone Prime has a "Draw until you have 6 cards" power, but without the putting cards at the bottom of the deck.

And Slowking Prime (which is easier to get out than Uxie Lv X) has the same power as Uxie Lv X except your opponent chooses. Plus, you can also use Slowking HGSS with it as well.