Hi, I hope some devs read the forums here. I'm releasing a developer tool I hope you'll find interesting:
Koi is a website based download & unpacking tool that can get wordpress on your site in under 60 seconds. Long story short Koi gives all the benefit of using shell access but in a very user friendly way. It is designed specifically for big PHP software like wordpress.
Since it takes nearly half an hour to upload an unpacked wordpress through FTP I would hope that a Koi like system would bring you closer to a consistent 5-minute install.
Anyway, please try it out and tell me what you think (and please report any errors). I'll be releasing the full source code including scripts to create & customize project downloads shortly.
You can try out installing wordpress 2.6 with Koi right now: Download http://koi.fullvolume.co.uk/repos/wordpress/download.phps and save it as download.php (or anything.php really). Upload this file (about 90kb) to an empty folder on your website and view it in your browser.
Koi is young and not properly released yet. The theory is sound (and accounts for safe mode & apache threads) but I need people like you to test it out on as many different servers as possible to make sure permission problems are not horrendous.