IMPORTANT MESSAGE FOR SPIDERFRIENDLY FORUMS:
This little piece of Google info came from a great
interview about Google's Page Rank and Term Vectors.
...while Google might spider your site, it won't be added to the database until someone else links to it.
I was guilty of this myself with the vbSpiderFriend here. I didn't want this link to be visible to my users-- or they might start demanding a bloat-free text only version of my forum! So I manually submitted my Archive to Google hoping it would be added to the database.
According to that article (and interview with a head Goog) if a website is an island-- with no links leading into it from anywhere-- it will never be added to the database. So! Lesson learned: you must put a link to your archive somewhere on your site that Google normally indexes each month. Also, your Page Rank will of course be higher since it was found and not submitted.