[T2DMan]

Getting the vBulletin url's corrected is certainly not a small task, and you have certainly done well getting this far. Yes, I happen to support the one rewrite that I consider does a 110% job at rewrites, but you are getting there.

I like the nextthread/prevthread per hosting talk but the archive seems to be broken there.

I have now read through all the posts here and it looks like you have got many things covered. But can I suggest that you add the following:

• That you recommend the use of the vbulletin option to have the archive linking directly to the actual threads. This gets the most Google PR/link value etc to the actual threads - this was an option I was able to get added to vBulletin 3.5.
• or - that your rewrite does the direct to url rewrite on the archive/sitemap.
• And that the thread url on the archive is rewritten.
• when the root forum url is linked, that instead of it being "/index.php", that it be just "/". Matt Cutts says Google is working on determining what url should be the correct url, but better that each site do it for themselves.

• You are working on the newpost/latest post? - in the pre 3.5 vBulletin, my rewrite kept the initial url, but then when it searched for the url in the php, it then did a 301 redirect to the proper url - correctly paginated. That general logic should be able to be coded for your plugins. Rather similar to what you have done for the nextthread/previous thread
• there will be other issues, but those are the ones I see at the moment.

Google SiteMap

Should be an easy job to either mod my vbgsitemap, or the vbseo one for your url's.

On page SEO

No mention of seo'ing of vBulletin is complete without talking about onpage SEO.

If the first words of the title are the words that you are optimizing for, then this phrase should also be in the meta description twice, in an h1, and then repeated in sentence/paragraph form immediately following the h1. Most people posting threads do not repeat the title in the text they write, so repeating it via a formula makes sense. In looking around the forums mentioned on this thread I have seen a few using my formula. In general, with a proper url rewrite (almost achieved here), plus great onpage SEO I have been able to get many vBulletin sites so that their forums and threads are all showing high on the SERP's.

And with good search phrase selection, those pages are then able to get good traffic for the forums.

The onpage hints are just the same as needed for any site, and can be found on most SEO pages, but I have some specific template changes mentioned on my Search Engine Optimize vBulletin 3.5 thread.