D40, D60 and D5000 are categorized under the same category - the presence of video mode doesn't make the D5000 an intermediate-level camera - it is still just an entry-level DSLR with video, that's all.

Besides, I don't think you should categorize them like this, because some pros can do with a D40 while newbies can't do crap with a D3x. More appropriately:

D40, D60, D5000 - Entry-level.

D80, D90, D300, D700 - Intermediate.

D3, D3x - Professional.