GNU Emacs 24.5 was released on April 10th. I'm in the process of setting up a dual boot Windows/Linux machine right now as I'm slowly moving away from Mac OS X, mainly because of the cost of the hardware but also because I don't like it that much as a Unix-y development environment anymore.
Xubuntu 14.10 only comes with Emacs 24.3 and it looks like 15.04 will "only" include 24.4 so now is a good time as any to manually install 24.5. Please note this is not a complaint about Ubuntu and its many contributors. They do a great job, I'd rather have a stable system comprised of well-tested packages and install the exciting, cutting edge stuff manually.
A manual "out of the box" install is actually pretty easy. I followed the instructions for installing 24.4 on UbuntuHandbook, substituting 24.5 where appropriate. I also installed Emacs in a user-local directory tree as I really don't like mixing system-wide tools that have been installed by the package manager and manually installed packages in the same directory tree. Yes, I'm weird like this.
All in all the install was completely hassle free and allows me to send a test blog post from Emacs 24.5 on my new Xubuntu box to the blog using org2blog as usual.
Update: The instructions linked to above also work for Ubuntu 15.04 - you have to rebuild your Emacs 24.5 for 15.04 as some of the dependencies have changed.