This could probably be cut down to a single query, but it’s early and I’m pre-coffee, so in the interests of productivity over elegance:
{assign_variable:wiki_path="http://www.example.com/index.php/wiki/"}
{exp:query sql="SELECT r.*,
p.page_namespace, p.page_name AS topic,
n.namespace_label AS namespace
FROM exp_wiki_revisions r, exp_wiki_page p, exp_wiki_namespaces n
WHERE p.last_updated = r.revision_date
AND n.namespace_name = p.page_namespace
AND r.page_id = p.page_id
AND r.revision_status = 'open'
AND r.wiki_id = 1
ORDER BY p.page_name"}
<url>{wiki_path}{namespace}:{topic}</url>
{/exp:query}
{exp:query sql="SELECT r.*,
p.page_namespace, p.page_name AS topic
FROM exp_wiki_revisions r, exp_wiki_page p
WHERE p.last_updated = r.revision_date
AND p.page_namespace = ''
AND r.page_id = p.page_id
AND r.revision_status = 'open'
AND r.wiki_id = 1
ORDER BY p.page_name"}
<url>{wiki_path}{topic}</url>
{/exp:query}
{exp:query sql="SELECT r.*,
p.page_namespace, p.page_name AS topic
FROM exp_wiki_revisions r, exp_wiki_page p
WHERE p.last_updated = r.revision_date
AND p.page_namespace = 'category'
AND r.page_id = p.page_id
AND r.revision_status = 'open'
AND r.wiki_id = 1
ORDER BY p.page_name"}
<url>{wiki_path}Category:{topic}</url>
{/exp:query}
Add the additional XML tags if you desire of course to have a well rounded Sitemap.