Please watch this short video to get an overview of Webfinger

http://www.youtube.com/watch?v=Y26c9MNQLyc

If you have an Identi.ca account or a Google account you already have an email [like] address that you can webfinger.

• create an account with a service that provides Webfinger metadata
• look up your meta data at http://webfinger.org/
• explore the information that was discovered

When you do a webfinger discovery on an email [like] address at somebody@example.org the process begins by asking for the URL http://example.org/.well-known/host-meta which will given the caller back an LRDD document with some  XML like the following

<?xml version="1.0" encoding="UTF-8"?>
<XRD xmlns="http://docs.oasis-open.org/ns/xri/xrd-1.0">

<hm:Host xmlns:hm="http://host-meta.net/xrd/1.0">example.org</hm:Host>

  <Link rel="lrdd" template="http://example.org/main/xrd?uri={uri}">

    <Title>Resource Descriptor</Title>

  </Link>

</XRD>

Using your webfinger provider:

• from your browser download the host-meta file and examine the contents of the file. Locate the template tag  . If you know your way around a terminal you could also ..  curl  http://example.org/.well-known/host-meta
• now look up the template URI switching {uri}  for acct:somebody@example.org i.e here we would look up http://example.org/main/xrd?uri=acct:somebody@example.org, again examine the contents of this file, what information is stored here about you?
• You will probably see your OpenID provider listed here explore how Webfinger can enhance the capabilties of OpenID 

For some more background you can read the following:

http://code.google.com/p/webfinger/