Apparently, the simple answer is no. According to Harvard's Water Maser Cosmology Project....

Today, the best estimate of the Hubble constant is uncertain by perhaps 10% when all things are considered.

Of course, in traditional astronomical terms, "uncertain by 10%" is astoundingly accurate.

Water masers do appear to have potential for modifying and giving us a more accurate distance scale. One interesting article I haven't seen mentioned is: A Revised Cepheid Distance to NGC 4258 and a Test of the Distance Scale by Jeffrey A. Newman, et al.

[Edit: Hmm. If that article link doesn't work for you, try this one.]

__________________
Everyone is entitled to his own opinion, but not his own facts.