webfinger for linked data

I've been interested in the webfinger technology for some time, which
allows you to get machine readable information about an email address

one use case for this is during the on boarding process when a user may
type in their email address and the system would like to use that as a
lookup key for profile data

webfinger is a way to do this (and I think part of ostatus) however imho it
suffers from a number of weakness, that I think can be easily fixed.

1. the mandatory serialization (JRD) is not 100% compatible with the social
syntax of this group
2. a new URI scheme (acct:) is used whereas for email mailto: is typical
3. the query used is subject= however email is often the object in a
statement "Bill HAS emaill <bill@example.com>

I propose to implement some simple changes that would fix this.

1. a lookup system lives in /.well-known/webfinger

2. it allows the query of the form ?object=mailto:bill@example.com

3. it returns linked data in line with the social syntax this group is
developing

Feedback is welcome.  I can go ahead and implement this today.  It may also
be of interest to activty pump and ostatus based systems.