It is common that people add their LinkedIn profile in their resumes. On the other hand, they add profiles (like ResearcherID) counting publications, citations, and showing factors such as h-index.
ResearchGate is something in-between, but I have not seen if anyone add his/her ResearchGate profile link in resume. Is it because ResearchGate is young and not popular, or it is not technically convenient?
The different services such as Researcher ID, ResearchGate, LinkedIn have not generally caught on in application processes (I am sure there are several exceptions). I am, however, sure these will become more common. To use the h-index provided in ResearcherID is one way to get a relative standard measure, compared to one calculated by each individual. Hence, I am sure these linkable sources will become more common in application procedures.
I use researcherID in my CV and am now on ResearchGate and will use their measures as well. Since they are official checkable soures I think they serve well in CVs. In my case, however, I have noticed that maybe 5-10% of the citations I can find in Web of Science cannot be found through Researcher ID, this is because some references occure as several entries due to errors in peoples reference lists etc. I believe it is possible to send in error reports to Web of Science to get corrections made. This means that the total number of citations through, for example, ResearcherID may be smaller than what you think you should have. But since this problem likely affects everyone in a similar way the values are still comparable, at least that is howI think about it.
So, I think it is fair and very useful to list these measures that can be independently checked. You could (should) check your field to see what services are often used and perhaps focus on those first.
I think the reason ResearcherID is sometimes used on CV's is because it's a quick way to link to (and host centrally) your publication list as well as bibliometric information (h-index, number of citations, etc.). I also see people use Google Scholar as an alternative service for that, although the quality of citation data is not as good.
For LinkedIn, it may be field-dependent. I see a large number of people around me (chemical engineering, both academic and industrial) semi-actively using it, i.e. maintaining a network of peers and getting the occasional introduction/reference through it. I do not often see it used in CV's, however. It is clearly used for networking.
ResearchGate, as you stated, is neither here nor there. It's not very widely used yet, and rather aims to be a "Facebook for researchers": it is centered around papers, comments and discussion. While it can be used to host a publication list, the metrics it offers access to are not commonly used and, one must say, rather opaque. I think that's why it has little value to add to a CV.
IMHO it would be better to have a web page containing the links to all the professional profiles you have (ResearchGate, LinkedIn, etc.), and give a link to this web page (rather than several links to separate profiles) in your CV.
