Gustaf, the version of ns_cache you recommend is UNRELEASED. We can't be distributing OpenACS requiring folks to get the basic prerequisites from CVS.
Until someone actually releases a new version of ns_cache that actually supports this feature, it makes sense to write code that will work without it.
Xowiki cannot be included in .LRN, for example, until we have an "official" ns_cache that supports the pattern agrument. Insiting on this kind of thing is why it is so hard to get OpenACS working. For you, getting ns_cache with a one-line change from CVS is no problem, me neither, but expectig a new user to hunt and find every little piece in a different place is not good.
I use the debian packages for AOLserver and the AOLserver modules and that version of ns_cache does not support the pattern argument either.
I asked before on the AOLserver list but noone seems interested in making the latest ns_cache available. If someone could do that it would be great.