@dave, @joel:

13,000 users isn’t a problem for PBwiki, though you probably wouldn’t want to use our general user management interface. We have some specialized power tools that admins who need to deal with those kinds of numbers can access.

You can definitely tie PBwiki IDs into LDAP, or better yet, simply use LDAP to authenticate access to PBwiki.

We can’t do too much about reassuring you about our continued existence other than to note that PBwiki has been around since 2005, has backing from a great bunch of investors like MDV and Ron Conway, continues to grow even during this downturn, and that we are frugal as heck and intend to be around for a long time.