Is there any Blueprint console (FBML-like) to test Blueprint markup? Combine this with the language reference, it would be indispensable!

Yes, we have a console which allows you to test and see your Blueprint markup available here internally and will soon release it to the public. I will add a note here in the forum as soon as it has been released but we will also let you know in our blog: http://mobile.yahoo.net/developer/blog