Update 05/09/09: since I originally posted this information it looks like the Webkit Team re-organised their PPA. I have updated the instructions - thanks to those who let me know.

I just installed the Epiphany Webkit 2.27.2 browser from the Webkit Team PPA. It seems pretty speedy - and the flash plugin can now used.

1. Add the Webkit Team PPA and Epiphany Webkit Team PPA repositories by adding the following lines to /etc/apt/sources.list:

   # Epiphany Webkit PPA
   deb http://ppa.launchpad.net/webkit-team/ppa/ubuntu jaunty main
   deb-src http://ppa.launchpad.net/webkit-team/ppa/ubuntu jaunty main
   deb http://ppa.launchpad.net/webkit-team/epiphany/ubuntu jaunty main
   deb-src http://ppa.launchpad.net/webkit-team/epiphany/ubuntu jaunty main
   

2. Add the Webkit Team PPA Key:

   wget -O webkit.key http://keyserver.ubuntu.com:11371/pks/lookup?op=get\&search=0x991E6CF92D9A3C5B
   sudo apt-key add webkit.key
   

3. Install epiphany-webkit:

   sudo apt-get update && sudo apt-get install epiphany-webkit
   

Not sure if this will replace Firefox on my desktop machine (I won't be able to give up my Firefox extensions). But I will certainly use this as my main browser on my netbook.