The parent here speaks the truth.
I notice a lot of the comments in the thread are coming from developers or sysadmins who want to solve everything with libraries or command line tools. But it really sounds to me like you need a reasonable document management system (and of course being a slashdot reader you want it for free).
Again, I'm not affiliated with Alfresco, but did quite a bit of research into open source DMS's that would run in a java environment for a couple of recent projects. I found Alfresco to be well architected, easily extendible if I needed it to be and importantly simple to deploy & get running. It will integrate with your LDAP for access and while it's marketed as an Enterprise CMS, is quite capable of doing DMS.
It uses Lucene under the hood, and while it has a web UI, isn't focused on indexing web sites. You can record meta-data against docs, and it's also capable of extracting some metadata from common MS Office formats. I've no doubt this could be extended if there were other doc properties you wanted access to (although I've never tried myself).
Most importantly is that the project & community is quite healthy with very active forums. You can get paid support (the Enterprise License) if you so desire, but I expect you'd probably start with the GPL version just to get yourself up & running.
I wouldn't recommend the SMB interface for the time being as there's currently an outstanding bug with it that causes it to die after a while (the rest of the app continues to run happily), however the FTP interface is great for an initial import of docs. Also take a look at the rules capability for classifying/sorting docs as they're imported.
It does the basics like check-in/check-out & workflow, and can be backed by your DB of choice as it uses Hibernate for ORM. Searching can be done against keywords or meta-data (classifications, dates, authors etc) & in my experience is more powerful/useful than sharepoints keyword based searching. If you're really keen you can use the Java or Web Service API's for integrating into other solutions.
Again, I'm not affiliated, but clearly I'm a fan-boy :) I'd recommend installing the base Alfresco Community release (no need for Web Content Management, Records Management etc to start with), loading some docs into it via the FTP interface (or upload a zip via the web interface which it will explode out for you) & giving it a test run. I've got people asking me every couple of days when we're rolling it out internally (just got to finish the sharepoint comparison first).
