As for who is and isn't playing, the top seeds on the men's side are Onischuk, Shabalov and Kaidanov; Kamsky and Nakamura are absent. (In Kamsky's case this is understandable - he's probably tired from the FIDE Grand Prix in Baku and might be preparing for the world championship semi-final match with Topalov. As for Nakamura, I have no idea why he isn't playing, and there doesn't seem to be any info on his blog explaining his absence. On the women's side, the US's (by far) two highest-rated women, Krush and Zatonskih, are both playing.
Here are the men's pairings for round 1:
1 Onischuk, Alexander 2728 - Kraai, Jesse 2569
2 Yermolinsky, Alex 2568 - Shabalov, Alexander 2709
3 Kaidanov, Gregory 2697- Friedel, Josh 2539
4 Fedorowicz, John 2514 - Shulman, Yury 2676
5 Akobian, Varuzhan 2666 - Ippolito, Dean 2512
6 Pruess, David 2497 - Becerra, Julio 2648
7 Ivanov, Alexander 2628 - Vigorito, David 2439
8 Ludwig, Daniel 2429 - Perelshteyn, Eugene 2626
9 Gulko, Boris 2623 - Kaufman, Larry 2384
10 Langer, Michael 2307 - Finegold, Benjamin 2613
11 Gurevich, Dmitry 2594 - Shankland, Sam 2299
12 Galant, Sergey 2176 - Kudrin, Sergey 2588

