Are you trying to Run XBMC Dharma or actually from the SVN? I would really suggest just running Dharma at this point. Also, the new folder structure for XBMC puts your addons (plugins) in ~/.xbmc/addons.
If you actually want to run SVN here are some steps to step it up so you can manage it via apt-get...
First install the Helper Tool used when compiling applications and libraries.
Now make your choice if you would like to install the 1. pvr-testing2 (unstable), 2. ppa (nightly) or 3. XBMC stable release. I've used SVN for a while now.
sudo apt-get install python-software-properties pkg-config
Let's make a system update.
1. sudo add-apt-repository ppa:henningpingel/xbmc
2. sudo add-apt-repository ppa:team-xbmc-svn/ppa
3. sudo add-apt-repository ppa:team-xbmc
Then we install the needed applications. (X server, Admin package for Also&OSS, Alsa driver configuration, Binutils, GGC, Power managment, udisk, policykit, XBMC audio)
sudo apt-get update
As, I said before I would suggest XBMC stable at this point. And you addons will go into ~/.xbmc/addons
sudo apt-get install xbmc xinit x11-xserver-utils linux-sound-base alsa-base alsa-utils binutils gcc upower udisks pm-utils policykit