I give big respect to Sony for their excellent hardware redesign and their new ad campaign, which is the best they've had this generation. The PS3 is looking a lot stronger now than when the year started, and they've certainly earned it.
On the flip side, the PSP is not doing a very impressive job right now. Hardware sales are steady, but software sales are DOA. Only one PSP title charts in the top 50 sellers of '09, three titles in the top 100, and I doubt that online sales are taking up much of that slack. The Go seems to be an experiment with little appeal to the market.
Microsoft has stirred up a lot of excitement with Natal. They've been marketing the technology aggressively to developers and enthusiasts, but concrete demonstrations seem a little thin. I'm not convinced that it's going to deliver on the promises it has made, and we've seen few other notable moves from MS this year. Right now, MS is more sizzle than steak and this is reflected in its recent unit sales.
Nintendo has lost some ground. The Wii is no longer the invincible juggernaut of '07 and '08. Chinks are visible in the armor thanks to a poor release schedule and perhaps some market saturation. Even though its market share is being eroded, Nintendo is still firmly in the lead, and this page shows it all:
http://www.vgchartz.com/yearly.php
Over half of the unit sales of hardware and software are still Nintendo, and Nintendo still dwarfs all other software publishers in the world in the console and handheld markets.
Sony is making some valiant inroads, but Nintendo just hasn't made enough mistakes to cost them the 2009 crown.

"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.







