probably a silly question that's been answered before, but is there any real discernible difference between the 8.9″ and 10.1″ versions? Basically is that extra inch worth 50 bucks is what i'm asking.

I'm sorry, but I can not get over the fact that these are called “Mini Mi”.

Doctor Evil: This is my notebook-style personal computing machine, only it is 1/3rd the size of the original. I shall call it … Mini Mi.

It is probably just a branding issue.
In Gentoo (build from source distro) there is a 'branding' option to
turn off the FireFox branding when you build it.

Hmm… I pulled up Synaptic but I'll be honest, I didn't try a
terminal. I'll head back over in a few minutes and try again.

It's also worth noting that this was a demo unit, so I wasn't able to
actually install any software since I don't have a superuser password.

The HP website says:

Please note: the Linux command line interface is disabled on this edition.

The rename of the browser just means they diddled some of the defaults from where Ubuntu had them. Moz Corp says you must have written permission to make ANY alteration to a binary package and retain the Firefox trademark. Which is why Debian calls it Iceweasel. They had no intention of seeking permission to apply a security patch. Ubuntu and RedHat have people willing to jump through the hoops. HP apparently found it simpler to just call it web browser, probably less flack from Microsoft that way anyhow.

I just added another photo – you can indeed open a terminal window and
use the command line interface.

I mean both have ssd type storage, run different distros of Gnu/Linux and similar overall specs.

I mean both have ssd type storage, run different distros of Gnu/Linux and similar overall specs.

No difference 8.9 vs 10.1 besides size. You dont gain REZ meaning you dont gain any more space within the LCD screen because it has the same amount of DOTS. Bummer. You lose battery life for the same Area LCD. The 10in is just bigger but not better. Rather have the 8.9 same rez 1024×600 and more battery life. IMO Unless someone has a hacked 10.2 in driver to bump up the rez or unlock the 10.1 Hidden /locked , “Never know with HP” Rez..
When you get yours, make sure the Keyboard isnt wavy and it doesnt hit the screen when closed. Also check your Ram Door Locks. Make sure they arnt broken. My new mini had one broken Lock for the mem door. They are sending me a Replacement fedex. The keyboard is a bit wavy on mine too, and I added foam Feet for the LCD lid Close height so it dont hit the keys closed.

There is some aesthetics differences too. The HP Mini 10.2 incher has a glossy “glass” layer that covers the entire thing, down to the bezel, (like many high end Sony's or the new Macbooks) while the 8.9″ doesn't (like the Asus EEE's).

Aesthetics, and the readibility wise, I'd spend the extra $50 for the 10″Er.

Many stores still carry the HP Mini 10″er with bluetooth and more for just $450, much cheaper than getting it off the HP site.

Regarding the command line interface; a user at Engadget says the following:

Harry @ Feb 5th 2009 1:24PM

The command line is there, the “disabled” thing HP had on their product page was misleading and probably cost them sales.

Not only can you activate a “root terminal” in the add/remove apps control panel, you can Alt-F2 to a standard gnome launcher and run gnome-terminal from there.