No plans for a "just in time" shuffle - this is a pain for not duplicating songs (especially when you remember there may be several power cycles during one playlist play).
However, we are adding functions like the original mp3mobile had, which allow you to resort the rest of the random playlist to have the next song from the same artist/album/year. Multiple presses of these buttons would each have an effect, so that (say) pressing 8 three times when listening to leftfield would make sure the next 3 tracks were from leftfield.
The new shuffle will produce an unshuffled playlist, then a shuffled play order, so you can switch in & out of shuffle as you want to.
Hugo