Is there a list of new functionality in 3.0?

One of the function that come very handy are the tempdata function that include in session class.

[/url][url=http://www.codeigniter.com/userguide3/libraries/sessions.html?highlight=tempdata#CI_Session::tempdata]Link

If you using 2.2 and you want to design a report page that contain pagination, after sending the limitation rules

EX:
start_date
end_date

you will realize that you only got few option:
url passing terms or
keep the terms in userdata
or  keep the terms in flashdata, but need to repeating the save the term in flashdata, this become very untidy.

with tempdata you can store the term for example 5 minute, when clicking next page you don't need passing value mechanism.

Have fun when coding.