System.Reactive puzzle

After working on the Reactive Framework with Erik, Wes and the rest of our team for over a year, it is great to see  that the word about System.Reactive is out (as described here, here, here and here).

I thought it might be fun to post a little puzzle challenge showing the power of the Reactive Framework. I asked the same question to my team members a while back and everyone got a different solution, from very declarative to very imperative.

here is the puzzle:

A while back, if found a jQuery implementation of tripple click of course this can be done very elegantly in Rx.

The first question is: can you implement this using Rx (for the Silverlight Button)? 
the second question is: can you generalize it like this:

public

static IObservable<RoutedEventArgs> GetMultiClickScan(this ButtonBase button, int count, int multiClickSpeedInMilliSeconds)

The third and final question is: Can you implement this without timers?

To give you a head start, here is the code to get an IObservable<RoutedEventArgs>that fires for each click:

var

click = Observable.FromEvent<RoutedEventHandler, RoutedEventArgs>
    (i => i.Invoke, i => button.Click += i , i => button.Click -= i).Select(e => e.EventArgs);

Rules:
-feel free to ask questions in the comments if you're stuck, can't promise I'll be able to answer you immediately or give everything away though :)
-feel free to post answers in the comments, if you don't want to be spoiled, don't read the comments :)
-No prizes, only eternal satisfaction with an awesome implementation can be won here :)

I'll post some of our teams answers to this puzzle in a couple of days..