I see this year's conferences as being Nintendo #1, MS #2, and Sony 3rd.
#1. Nintendo has what I call the trifecta of megatons this year; Zelda Wii, Wii Vitality/ Wii Relax, and 3DS. That alone should be enough to make for an excellent show, not to mention all the surprises we don't know about yet. They have several games already announced at their desposal to show off; Wii Party, Metroid Other M, The Conduit 2, Pikmin 3, Last Story, Xenoblade, Zangeki, Epic Mickey, etc. I also think we will see some more motion plus games. At least I hope so. Nintendo needs to prove that the motion plus upgrade is worth it.
#2. MS will have some stellar new games like Gears 3, maybe something new and exciting from Rare for a change, and of course Natal, which should turn some heads, though I don't see it having much of an impact besides maybe a few fun gimmicky games. It will be like the Wii controller; it will work excellent with certain genres and provide really fun unique experiences, but will also be highly flawed and akward with some genres as well. If MS prices Natal below $100, they might have a shot of making this a success. If it's $150 or more, it will be doomed to failure, as it's not easy to make a successful console add on. And I'm not sure everybody wants to game for long periods of time standing up and moving their entire bodies around. In a sense, every game becomes like Wii Fit in terms of physical movement. Because of this, I sense an angry backlash from MS core fanbase.
#3. Sony seems to be behind the curve. They will no doubt be showing off their "innovative" Move that which will be filled with demonstrations of Wii copied party games and a few core games with motion control tacked on. Most people will simply say, "ok, we saw this 4 years ago.. who cares?" I imagine some Move games will be good, but like Wii, many will be meh, and without that "new" factor, it will be forgotten about soon. They will likely show off a strong library of games, but most appear to be sequels, LBP 2, Socom 3, GT5, Killzone 3, etc.. In other words, I can't see too much of the "wow" factor coming from Sony's conference, as in surprising announcements.