Groups did receive updates several months ago, though the changes amounting to a search function and shuffling the memberlist were relatively minor. Join requests were a distinct possibility at the time, but never happened. With the badge frenzy and the subsequent release of the Nintendo 3DS, work on 3DSPaint became priority, leaving groups on the back burner remaining largely forgotten. I'm confident Groups v2.0 will still happen, hopefully before the year's end.
Well, if I'm right, 3DSPaint should have nothing to do with it, since it is basically just a re-sized copy of DSiPaint.
If Danny wants to focus on 3DSPaint, then he should start with Groups.
Then copy and paste the new programming and use it for DSiPaint's Groups.
HB is priotizing his work on here meaning that if anything needs to get urgently addressed it goes to the top of the "list" therefor giving an estimate is difficult and the only one possible of doing so would be HB.