We have an existing Trac installation for an old bunch of source code, and I'm creating a new Trac installation to support a new bunch of source code. Most of the info we've built up over time in the old Trac installation's wiki is equally relevant for the new Trac wiki.
Is there a quick way to migrate the wiki data from the old Trac to the new Trac?
Trac version = 0.10.4
It's all stored in the database, as far as I can remember. You should just be able to export the data from the old database and into the new one.
You should be able to use trac-admin to backup the wikis and then restore them on the other instance.
Use trac-admin <trac-env> wiki dump <some-directory> to dump the wiki pages to a directory, then use trac-admin <new-trac-env> wiki load <some-directory> to load the wiki pages into the new environment.
Note that I don't think this will preserve wiki page history. If you want that, you can copy the database to the new instance and do a resync to the new repository.
I would also recommend upgrading to 0.11 if you can. 0.10 is no longer supported, and 0.12 is due out "soonish".
Disclosure: I'm one of the Trac devs