After being spoiled with Git, I, along with many other developers, are dropping their subversion support in favor for git. From now on, you can grab the latest version of SMS Fu directly from GitHub. Feel free to fork it and contribute some changes here.
Also, unless you're on Edge rails you can install SMS Fu by doing the following below:git clone git://github.com/brendanlim/sms-fu.git vendor/plugins/sms_fu