I've been tracking sales numbers using VGChartz since September and thought I'd share a few findings. Now, it is a bit difficult to correlate Nintendo units sold, to retail units sold because of lag time, and because nintendo sells bulk to retailers, and copies then sit on the shelves. This is mitigated somewhat by the fact Nintendo items are flying off the shelves pretty fast.
Regardless the hardware sales numbers match up pretty well with Nintendos. The Wii software numbers match up as well, the DS software numbers are off though.
Starting with the week of Jan 5-11th (to negate holiday season numbers).
The Wii Console has sold in successive weeks 212k, 259k, 314k, 344k, and 438k units. So we're seeing a nice rise since the holidays.
Wii software has gone 1.5 mil, 1.7 mil, 1.9 mil, 2.7 mil, and 2.3 mil since then. (The 2.7 mil spike being Wii Fit and SSMB in Japan I'm guessing).
Again, a nice trend upwards.
DS Hardware has gone 341k, 412k, 390k, 383k, and 364k, so it's staying pretty level. Software has gone 1.7 mil, 1.7 mil, 1.6 mil, 1.5 mil, 1.5 mil. So again, staying fairly level.
Nintendo has forecast it will ship 4.3 mil Wiis, 5 mil DS's, 31 mil Wii titles, and 32 million DS titles in the Jan-Mar quarter. Reconciling Nintendo numbers to retail outlet numbers is difficult, but it looks like they are on track to beat Wii Hardware sales by 20% or more if the trend keeps pace. That seems like the easiest metric to use since they are selling everything they ship.