site

You could do something like:

--- mailhgrc.old    2010-08-28 22:27:24.639525837 -0400
+++ mailhgrc    2010-08-28 23:32:37.413137504 -0400
@@ -10,7 +10,7 @@
 # Don't send mail yet...
 test = True
 # Number of leading path elements to lose, like diff -p
-strip = 0
+strip = 2
 # Domain to use for addresses lacking one
 domain = illumos.org
 # Style file to use to format the message
@@ -30,7 +30,7 @@

 [web]
 # Base of the HTTP-accessible repo
-baseurl = http://hg.illumos.org/illumos-gate
+baseurl = http://hg.illumos.org/

 # These can be in a separate file, pointed to by the 'config' key in the
 # [notify] section.
--- mailstyle.old    2010-08-28 22:26:58.839917515 -0400
+++ mailstyle    2010-08-28 22:30:39.563940642 -0400
@@ -1,7 +1,7 @@
-changeset = '\nchangeset:   {rev}:{node|short}\n{branches}{tags}{parents}user:        {author}\ndate:        {date|date}\n\ndescription:\n\t{desc|strip|tabindent}\n\n{file_mods}{file_adds}{file_dels}{file_copies}\n'
-changeset_verbose = '\nchangeset:   {rev}:{node|short}\n{branches}{tags}{parents}user:        {author}\ndate:        {date|date}\n\ndescription:\n\t{desc|strip|tabindent}\n\n{file_mods}{file_adds}{file_dels}{file_copies}\n'
+changeset = '\nchangeset:   {rev}:{node|short}\ndetails:     {baseurl}{webroot}?cmd=changeset;node={node|short}\n{branches}{tags}{parents}user:        {author}\ndate:        {date|date}\n\ndescription:\n\t{desc|strip|tabindent}\n\n{file_mods}{file_adds}{file_dels}{file_copies}\n'
+changeset_verbose = '\nchangeset:   {rev}:{node|short}\ndetails:     {baseurl}{webroot}?cmd=changeset;node={node|short}\n{branches}{tags}{parents}user:        {author}\ndate:        {date|date}\n\ndescription:\n\t{desc|strip|tabindent}\n\n{file_mods}{file_adds}{file_dels}{file_copies}\n'
 changeset_quiet = '{rev}:{node|short}\n'
-changeset_debug = 'changeset:   {rev}:{node}\n{branches}{tags}{parents}{manifest}{extras}user:        {author}\ndate:        {date|date}\ndescription:\n\t{desc|strip|tabindent}\n\n{file_mods}{file_adds}{file_dels}{file_copies}\n'
+changeset_debug = 'changeset:   {rev}:{node}\ndetails:     {baseurl}{webroot}?cmd=changeset;node={node|short}\n{branches}{tags}{parents}{manifest}{extras}user:        {author}\ndate:        {date|date}\ndescription:\n\t{desc|strip|tabindent}\n\n{file_mods}{file_adds}{file_dels}{file_copies}\n'
 start_files = 'files:\n'
 file = '   {file}\n'
 end_files = ''

The baseurl change is necessary because I screwed up.
the webroot macro is based on the path to the repository, as then molested
by the [notify] strip setting, which in the case of illumos-gate is currently
incorrect (It should be one more than it actually is, so it shows as 'illumos-gate'
not, 'hgrepos/illumos-gate')

The diffs above will probably not apply cleanly, being based on the files I sent to
Garrett, not necessarily the files in use (for instance, the strip line probably has the value '1', currently)

This is completely untested.