As of July 15, 2007 Wii has reached 40% marketshare in current console market (Wii, PS3, 360) with sales of 9.3 million out of 23.22 million.  While many had expected a PS1 like build up of momentum for the Xbox 360 - save Japan of course - the 360 has just under 44% marketshare worldwide right now, after entering 2007 with ~63% of all current gen console sales to date.  This can be attributed to 2007 sales - in which Wii has ~56% of all current gen sales, while over the comparable time period Xbox 360 has ~ 22% of all current gen sales. 

Nintendo has not had 40% marketshare in a console race since the waning days of the SNES as the world's dominant console - in 1994 to early 1996 (right before PS1 started to take off worldwide).

During its 33 weeks on sale worldwide Wii has sold an average of 281,819 consoles each week - often outselling PS3 & 360 combined.  If that 33 week average continues through the end of 2007 (and it might since it includes a holiday sample and a non holiday sample) Wii will be at 16.06 million units worldwide.   

Here is my estimate of Nintendo's market trends since the NES...with 'foes' indicative of who composes each generation.

Console         Peak Market Share Worldwide          Avg. Marketshare Worldwide      Foe(s)

NES                     80-85% (1988)                                        ~70%                               PC Engine, Master System  

SNES                   60-65% (1995?)                                        ~ 50%                            Genesis, Turbographx, 3D0

N64                     30-35% (1997)                                        ~ 27%                              PS1,Saturn

GC                      17-20% (2003?)                                       ~ 14%                             DC,PS2,Xbox

Wii                      55-60%?? (2008/2009)                           ~45%??                          PS3, Xbox 360

With Wii continuing to outsell each of its rivals worldwide anywhere at 2:1 to 4:1 clip expect the marketshare to grow at least another 10-15% in the short term. 

Oh, peak market share. That is a good analysis. Very interesting.

Incredible. The 360 just can't compete without decent Japanese sales.

I am pretty sure Nintendo is orgasmic right now (hell they must have been orgasmic for the past several months now). But this shows that a low-price console appealing to more than core gamers can be very successful. Oh, and recent data does show that Nintendo has been stockpiling their Wiis, so maybe all the will consumers might be able to find it during christmas.

I would not say all, but more.

That's very impressive. I can't see it reaching NES levels with so much competition - but if they can take SNES levels of marketshare this generation - they will be stoked (and 99% of analysts will have to eat their hats!).

The days of people comparing the Wii to the GC are well and truly over ;)

I still think NES levels are possible.

Simply because Wii is shaping into a cultural phenomenon.

It's all up to the conversion of casual people now into gaming. If Wii actually can get people into the gaming hobby that were never there, the numbers and new levels of market share will really trump the historical data we have to compare with it as the dynamics of the marketplace as a whole are aimed differently.

And towards it's 50 % marketshare worldwide (this year, almost guaranteed), and higher. :p