To back up Mark’s claims:
I could be wrong but I agree with Sock Puppet that I think it would be more likely for 1.6.5 to come out first.
There are some PHP based solutions you could use if you search the forums, Zuul, but 1.6.5 is coming in days, not weeks, so it may be best to wait for that update.
So, as of the 16th, 1.6.5 was coming in days. It has been a little over a week, but who’s counting.
I think that as long as you haven’t used too many 3rd Party modules, extensions and plugins on any sites that you want to upgrade to 2.0 then you should be okay. I think that there are only very minor changes that will be needed to some of your template tags.
That’s the goal. We see 2.0 as an update, not as a separate system. There will be some changes needed, mostly around any third party add-ons you’ve got, but for most EE users it won’t be much more involved then any other version update.
Straight from the horse’s mouth…as they say.