Importing changes from my branch. There are two major updates:

1) I wrote a function that formats output from scripts in a consistent way. Although we haven't really come to a concensus on how it should look yet, it's easy to change when we do. 
2) New script: smb-enum-groups.nse. Enumerate the local groups on a system and their membership.

scripts/smb-enum-groups.nse

@@ -0,0 +1,92 @@
+description = [[
+Obtains a list of groups from the remote Windows system, as well as a list of the group's users. 
+This works similarly to enum.exe with the /G switch. 
+
+The following MSRPC functions in SAMR are used to find a list of groups and the RIDs of their users. Keep
+in mind thatMSRPC refers to groups as 'Aliases'. 
+
+* <code>Bind</code>: bind to the SAMR service.
+* <code>Connect4</code>: get a connect_handle.
+* <code>EnumDomains</code>: get a list of the domains.
+* <code>LookupDomain</code>: get the RID of the domains. 
+* <code>OpenDomain</code>: get a handle for each domain.
+* <code>EnumDomainAliases</code>: get the list of groups in the domain.
+* <code>OpenAlias</code>: get a handle to each group.
+* <code>GetMembersInAlias</code>: get the RIDs of the members in the groups. 
+* <code>Close</code>: close the alias handle.
+* <code>Close</code>: close the domain handle.
+* <code>Close</code>: close the connect handle.
+
+Once the RIDs have been termined, the
+* <code>Bind</code>: bind to the LSA service.
+* <code>OpenPolicy2</code>: get a policy handle.
+* <code>LookupSids2</code>: convert SIDs to usernames. 
+
+I (Ron Bowes) originally looked into the possibility of using the SAMR function <code>LookupRids2</code> 
+to convert RIDs to usernames, but the function seemed to return a fault no matter what I tried. Since 
+enum.exe also switches to LSA to convert RIDs to usernames, I figured they had the same issue and I do 
+the same thing. 
+]]
+
+---
+-- @usage
+-- nmap --script smb-enum-users.nse -p445 <host>
+-- sudo nmap -sU -sS --script smb-enum-users.nse -p U:137,T:139 <host>
+--
+-- @output
+-- Host script results:
+-- |  smb-enum-groups:
+-- |  |  WINDOWS2003\HelpServicesGroup: SUPPORT_388945a0
+-- |  |  WINDOWS2003\IIS_WPG: SYSTEM, SERVICE, NETWORK SERVICE, IWAM_WINDOWS2003
+-- |  |  WINDOWS2003\TelnetClients: <empty>
+-- |  |  Builtin\Print Operators: <empty>
+-- |  |  Builtin\Replicator: <empty>
+-- |  |  Builtin\Network Configuration Operators: <empty>
+-- |  |  Builtin\Performance Monitor Users: <empty>
+-- |  |  Builtin\Users: INTERACTIVE, Authenticated Users, ron, ASPNET, test
+-- |  |  Builtin\Power Users: <empty>
+-- |  |  Builtin\Backup Operators: <empty>
+-- |  |  Builtin\Remote Desktop Users: <empty>
+-- |  |  Builtin\Administrators: Administrator, ron, test
+-- |  |  Builtin\Performance Log Users: NETWORK SERVICE
+-- |  |  Builtin\Guests: Guest, IUSR_WINDOWS2003
+-- |_ |_ Builtin\Distributed COM Users: <empty>
+-----------------------------------------------------------------------
+
+author = "Ron Bowes"
+copyright = "Ron Bowes"
+license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
+categories = {"discovery","intrusive"}
+
+require 'msrpc'
+require 'smb'
+require 'stdnse'
+
+hostrule = function(host)
+	return smb.get_port(host) ~= nil
+end
+
+action = function(host)
+	local status, groups = msrpc.samr_enum_groups(host)
+	if(not(status)) then
+		return stdnse.format_output(false, "Couldn't enumerate groups: " .. groups)
+	end
+
+	local response = {}
+
+	for domain_name, domain_data in pairs(groups) do
+
+		for rid, group_data in pairs(domain_data) do
+			local members = group_data['members']
+			if(#members > 0) then
+				members = stdnse.strjoin(", ", group_data['members'])
+			else
+				members = "<empty>"
+			end
+			table.insert(response, string.format("%s\\%s (RID: %s): %s", domain_name, group_data['name'], rid, members))
+		end
+	end
+
+	return stdnse.format_output(true, response)
+end
+