I wondered whether it's possible to see which sites you trust with your LiveJournal OpenID and got pointed to http://www.livejournal.com/openid/options.bml, which I see is linked to from http://www.livejournal.com/openid/.
But I'm not sure whether it's otherwise discoverable. There are three FAQs with "OpenID" in their titles (and four more that can be found by searching the FAQs for "OpenID"), but none of them seem to fit; the closest is FAQ #283 in the Account Levels category, "What is an OpenID account? How can I create and use one?", but that's more about logging into LiveJournal with an OpenID from another site than about using your LiveJournal OpenID to log into other sites.
So, perhaps a new FAQ is in order mentioning your use of OpenID.
Oh! Wait. After re-skimming the seven FAQs that the search found, I see that the OpenID settings page is linked to at the bottom of FAQ #231, "What is OpenID commenting? How do I use it?", in the last paragraph. But that paragraph doesn't seem to have much to do with the remainder of the FAQ, and I certainly wouldn't have looked for that information in a FAQ in the "comments" category. I almost suspect that the information was stuck there because no better place could be found for it than because someone decided it belonged there.
At any rate, what do you think about putting that information in a separate FAQ? Perhaps in the "Working with Other Sites" (ext_sites) category?
Or at least putting in a sub-header in the FAQ before the last paragraph to catch the eye?