I saw the new recaptcha v2 a while back. Unfortunately they do not provide a .net webforms control, they only provide a javascript api and it is very non-trivial to implement a control for this that can work in all the needed contexts such as inside an ajax updatepanel. It took me quite a bit of time and work to get the previous version of recaptcha to work in those scenarios, I had to modify the .net control they provided in order to make it work inside an updatepanel.

I'm too busy on other things to try and take that on right now, but I will keep an eye out for them or someone else to provide an implementation that is easier to plug in.

of course if there are other developers in the community who would like to develop and contribute a wrapper control for this, it would be a very welcome contribution.