Wii will overtake SNES(44 million) install base before end of 2008.

[superchunk]

As of this posting time VGC has Wii @ 31.12m sold.

Based on the link below the Wii is selling about 350k per WEEK. (~1.4m/month)
http://vgchartz.com/hwcomps.php?cons1=Wii&reg1=All&cons2=PS3&reg2=All&cons3=X360&reg3=All&start=39313&end=39677

There are about 9 weeks before Holiday sales really start to kick off.
350*9 = 3.15m, which bring Wii to ~34.27m by the week of October 19th.

Last year from Mid October through the end of the year Wii sold ~6.74m units.
http://vgchartz.com/hwcomps.php?cons1=Wii&reg1=All&cons2=PS3&reg2=All&cons3=X360&reg3=All&start=39376&end=39453&weekly=1

Last year's monthly production was about 1.8m/month. This year's monthly production is about 2.5m. That's and increase of about 28% in supply. Given that Nintendo follows the same stockpiling plan of last year by percentage and the demand still out strips supply, You should see a similar increase in sales as compared to last year.

6.74 * 1.28 = 8.63m.

34.27 + 8.63 = 42.9m would be my lowest expectation. I still think Wii will end around 45m this year.

So, no, Wii will not beat SNES (49m) this year. But it will do it by the end of March 2009.