Some important items, such as ajax or lowering the pain of creating components was already discussed on blog from Ed Burns or other JSF spec members.
I filed some tickets in the past against the JSF Spec (meaning API definition) as well.
Here is my (incomplete) list:
I want more interfaces on javax.faces.component:
https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=322
Why does Unified EL Spec say If A is String: return A. Otherwise, if A is null: return “”.
https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=323
I can understand why they added this guy in UIInput, but IMO this is wrong:
https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=327
(Please no EditableValueHolder2
)
Autocomplete was introduced on inputText, with the advent of JSF 1.2 (due to the rise of ajax),
but they forgot the html_form component:
https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=418
I am pretty sure some more methods are missing on ExternalContext:
https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=438
In Trinidad we have a ExternalContextUtil, where we add those bits that are missing…
Why not making subforms part of the standard (since jsf 2.0 already contains some new tags):
https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=441
These came up due to bugs, Gabrielle Crawford and I worked on (since our ADF Faces Framework has an optimized JSF lifecycle):
-https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=331
-https://javaserverfaces-spec-public.dev.java.net/issues/show_bug.cgi?id=332
I hope these tickets (and some others) are addressed in the next generation of JSF 2.0 
Some other cool things were already added, as Ryan showed in his blog. I am really looking forward for the JSF.next (and for Servlet 3.0 as well).