The more I explore 3.0, the more nice surprises I have. It is truly impressive that so much attention has been paid in enhancing user experience and efficiency in info management and customisation.
Just found out that (1) group tag looks different from ordinary tag in tag bar. This feature and together with custom-colour tag are very useful in spotting the different nature of tagging in one snapshot (2) I can customise the list of choices of fields to be displayed in column view, now I can choose my column from a much shorter list of my favourites instead of searching through all metadata. (3) I am increasing aware that with the rich set of actions and triggers offered in smart rule, and batch processing, there aren’t much needs for custom scripts. I look forward to seeing more actions to be added to the smart rule in the future. I hope/suggest the help document will enrich the explanation of various triggers and action in smart rules with some more examples in the next version update,
OR
Given the lower cost of publication of ebooks. I think someone like Jim and cgrunenberg and some very experienced user (specially Korm) should consider co-authoring a book, by extending and elaborating from the help document, to teach users of all levels to maximise the utilisation and customisation of 3.0 - with lots of examples. With the long version cycle of DT, I think the copies will/can be sold for many years!
And scripts can be easily embedded into smart rules too if the default actions shouldn’t be sufficient.
I just discovered that annotation files are now visible and editable directly on the right hand side of the main window. this means i no longer have to click and open annotations and arrange them on the screen, they appear automatically when i scroll through a list of research (pdf) articles in my research database. How cool is that 
There is already an English tutorial by Joe Kissell. And (sorry for the self-promotion) a German introduction written by me. The update for DEVONthink 3 is in progress - I think I will finish it until the end of this month
Wow, that sounds useful! Could you, please, put a screenshot of how it looks like (with some non-private pdfs maybe) for those who are interested in DT3.0, but aren’t courageous enough for trying beta? 
I hear you on the annotations! I never really liked having my notes separate from the file they were commenting on. Now, not only are they together, but all the annotations already made in v.2 are right there in the Inspector tab - no c+ping necessary. Very cool, thanks guys!!