I saw the the news that emacs 23.1 was released.
For a programmer, What are the big reasons to upgrade? I'm currently on 22.2.
None of the features listed really seem like must-haves for me. The most immediately interesting bit is that nXML is now integrated. I already have it though.
But I have to admit I don't know what is really behind "smarter minibuffer completion" or "per buffer text scaling".
Anyone have any tips or examples of what these things are?
For me, the biggest reason is the support for anti-aliased fonts. And the --daemon support is nice.
Emacs-fu has a nice write-up of some of the features.
"Improved Unicode support (the internal character representation is now based on UTF-8)." is a critical reason for me, but it no doubt depends on your work flow.
Some of the terms you are asking about were discussed in http://stackoverflow.com/questions/534307/set-emacs-defaut-font-face-per-buffer-mode and are also in the emacs wiki, e.g. http://www.emacswiki.org/emacs/SetFonts (under Changing Font Size - Buffer Text Resizing ).
While I was using the pre-releases, the most noticeable feature has been the improved font support. and some small things about smarter window splitting.
for me its font support and gnupg integration.
also its nice to read pdf's from within emacs.
No one said anything about multi-tty support? I have one long (LONG!) emacs session opened somewhere, and I ssh'ed into that machine remotely and use that particular emacs session (with all the temporary buffers, everything setup the way I liked, groups of buffers opened, etc.). The benefit of course, is that I don't need to worry about saving temporary buffers (you do use those as scratch pad, don't you?), etc. when switching machines (from school to home, for example).
Also, with multi-tty support, you can open emacs with emacsclient -nw to substitute your occasional needs for vi for quick terminal edits. emacsclient -nw will open even faster than vi, and you will have access to your opened emacs session as a bonus. (Before emacs 23, emacsclient cannot run from the terminal).
You can display week numbers in calendar by customizing calendar-intermonth-text. I have been waiting a long time for this feature. In previous versions of emacs only custom hacks were available.