You can test it, but my guess is that it should still work. Some variable structures might not, but the plugin should be largely unaffected.
I've tested it, Yumi (MyBB 1.6.4 released now).
It seems that all of my conditionals in "my" forum work
I dread these updates but I like to stay current! Do you think this update will affect any plugins across the board? I have a ton installed! LOL
Run a copy of your forum on localhost and try upgrading there to see if it works.
OK, I just bit the bullet and went for it on my live board!
Had a problem with Google SEO and had to re-upload the function.php file from the plugin and that fixed everything up! Otherwise, the only other problem was Proportal needed the portal.php file re-uploaded from the plugin in order to bring my custom portal page back to life! All in all, it wasn't too bad! I did not deactivate any plugins during the upgrade!
Zinga, what are your predictions on XThreads compatibility with MyBB 2.0 when ever it may come to life?
I don't think any MyBB 1 plugin will be compatible with MyBB 2.