Here is a script that will do absolutely everything - including downloads - in order to get a compiled version of bitcoin working in Natty (with the GUI fixed of course):
http://pastebin.com/JLxKKpuqActually, I'll even put it here directly:
#!/bin/bash
echo "DISCLAIMER: you are using this script at your own discretion! By typing 'c', you agree that you have read the script yourself and have understood it and that you will thus take full responsabilty in the eventuality that this script leads to any harm to you or your property. If you do not agree type 'n'"
read -n 1 r
[ "$r" = 'c' ] || exit 0
set -e
echo "You will be prompted to enter your password in order to install necessary dependencies."
sudo apt-get install build-essential libgtk2.0-dev libssl-dev libdb4.7-dev libdb4.7++-dev libboost-all-dev
sudo apt-get build-dep libwxgtk2.8-dev
mkdir bitcoin || true
cd bitcoin
[ -e wxWidgets.tar.gz ] || wget "http://biolpc22.york.ac.uk/pub/Daily_HEAD/wxWidgets.tar.gz"
[ -e wxWidgets ] || tar -xvzf wxWidgets.tar.gz
cd wxWidgets
./configure
make -j3
sudo make install
sudo ldconfig
cd ..
[ -e miniupnpc*.tar.gz ] || wget "http://miniupnp.tuxfamily.org/files/download.php?file=miniupnpc-1.5.tar.gz"
[ -e miniupnpc*/ ] || tar -xvzf *miniupnpc*.tar.gz
cd *miniupnpc*/
make
sudo make install
cd ..
#for some reason, github's certificate doesn't work:
[ -e bitcoin*.tar.gz ] || wget --no-check-certificate "https://www.github.com/bitcoin/bitcoin/tarball/v0.3.21"
[ -e bitcoin*/ ] || tar -xvzf "v0.3.21"
cd bitcoin*/
make -f makefile.unix
make -f makefile.unix bitcoind
#optional:
strip bitcoin; strip bitcoind;
echo "Bitcoin is now compiled : '$PWD/bitcoin'"
echo "Launch bitcoin now? (y/n)"
read -n1 r
[[ "$r" = y ]] && ./bitcoin
cd ..
To run it: save it in your home folder as bitcoinfornatty.bash, open a terminal (ctrl+alt+t), type "bash ./bitcoinfornatty.bash", press enter (yeah, some people don't even get that you have to press enter) and READ THE DISCLAIMER.
Also, you agree that I will not be held responsible for any inconsistencies between my disclaimer and the amount of detail in my instructions.
Don't hesitate to report any problems.
EDIT: added lines:
make -f makefile.unix bitcoind
#optional:
strip bitcoin; strip bitcoind;
It will now build bitcoind also.