SEO features by default would really make MyBB the best among free forum softwares. I'm not 100% sure but I think search engine friendly URLs are only in the paid forums by default.
So, what I'd like to see is:
- SEO friendly URL (mod_rewrite)
- XML sitemap
- Meta data
Yea, I think Google SEO should come with MyBB itself. It's a great plugin.
Yeah, it would be great to see the SEF side of things boosted greatly, it is currently a weakness in MyBB you'd have to say. And there is free forum software that used SEF URL's out there.
Friendly URLs have very little these days for SEO. Consider Digital Point or Hack Forums if you don't believe me.
Apart from that, I do agree that MyBB 2.0 should have improved SEO options. Having rel="canonical" built-in along with header/p/div tags would be great in MyBB 2.0 (but the default 2.0 theme already has confirmed to have no tables).