How do I upgrade MySQL to 5.5, am I best off waiting for it to be available through apt-get?

What's New in MySQL 5.5

Here are some recent improvements to the speed, scalability, and user-friendliness of the MySQL database and the InnoDB storage engine.

A step by step guide to upgrading to MySQL 5.5

This doesn't solve your problem but here's the wishlist bug for packaging MySQL 5.5.

A good option might be to wait for a version from dotdeb.org. Once it's available in Debian unstable/experimental, there will be packages available there.

http://www.dotdeb.org/tag/mysql/

I have sucessfully installed MySQL-5.5.15 into Natty (Ubuntu 11.04) with alien from official binary RPMs.

Install alien and libaio1 (used from MySQL-5.5)

apt-get install alien libaio1

Fetch binary RPMs from MySQL downloads

$ wget -i -
ftp://MIRROR_SERVER/pub/mysql/Downloads/MySQL-5.5/MySQL-client-5.5.15-1.linux2.6.x86_64.rpm
ftp://MIRROR_SERVER/pub/mysql/Downloads/MySQL-5.5/MySQL-devel-5.5.15-1.linux2.6.x86_64.rpm
ftp://MIRROR_SERVER/pub/mysql/Downloads/MySQL-5.5/MySQL-server-5.5.15-1.linux2.6.x86_64.rpm
ftp://MIRROR_SERVER/pub/mysql/Downloads/MySQL-5.5/MySQL-shared-5.5.15-1.linux2.6.x86_64.rpm
^D

Convert them!

fakeroot alien MySQL*.rpm

...and, install them.

sudo dpkg -i mysql*.deb

Add mysql user

useradd -r mysql

Initialize data directory

mysql_install_db --datadir=/var/lib/mysql --rpm --skip-name-resolve --user=mysql

Set other necessary paths

mkdir /var/lib/mysqld
chown mysql /var/lib/mysqld/

mkdir /var/log/mysql
chown mysql /var/log/mysql

Start DB

service mysql start

Change the root password

/usr/bin/mysqladmin -u root password 'your_password'

There ist a brand-new ppa (personal package archive) repository which includes - beneath other things - mysql5.5 for natty and oneiric:

https://launchpad.net/~nathan-renniewaldock/+archive/ppa

It may be added to your system using this commands:

sudo add-apt-repository ppa:nathan-renniewaldock/ppa
sudo apt-get update