I have a question regarding parking good value domain. A client has a great website 'A' with page rank of 5 and a lot of traffic. They want to change the URL and redesign the site. So they have parked the domain 'A' and will later redirect it to the new domain, this will be in a month time. My questions is, by parking the old domain 'A' would they have lost its SEO value or will it be given to the new URL once they place a 301 redirect on it. Also, would it not have been better not to park domain 'A', keep it live and just redirect it once new domain goes live, notifying Google in Webmaster tools?
Very risky as it will likely lose some authority and it won't pass on all anyway but likely less for doing such a thing...
It will be better off making domain A stay live than just parked it, We all know PR = how google trust you. PR update roll outs every 3 months or so, so with that in mind, Using 1 month out of that time frame just parking the domain will surely give negative effect. So yeah to summarize, Don't parked the domain, keep it live then redirect it to new domain as soon as its ready ( in regards to On Page Optimization).
I won't suggest to park or redirection, instead create a page on your domain, it would be good from both point of views, users and search engines.. If you have plan to develop in future, then post that information on the website so the visitors would get aware of that, you can provide the means of contacting you as well, if they have any questions.