I don't understand your remark. There was a lighning version out just after TB5 just to make TB+lighning users working.
See http://weblogs.mozillazine.org/calendar/2011/07/lightning_10b4_has_been_releas.html

Windows :
Ok, looks like recent setup wizard are intelligent enough to not reinstall the same dll twice (or override a newer dll)
but if application A install DLL version 1.03 in its own directory and system has DLL 1.02, then there will be two dll loaded in memory, one for appli A, one for other applis using the lib...

Linux(and Unix) :
version number are part of the file name, which mean you can have several versions in the same directory without overrriding by error a newer version.
you can have libc.so.1.12.3, libc.so.1.13.4, libc.so.2.0.0
APP A can link with libc.so.1 and so will use libc.so.1.13.4 in reality
APP B can link with libc.so.1.13 -> will use automatically libc.so.1.12.3
APP C can link with libc.so -> will use latest, libc.so.2.0.0
I think windows should copy and put the dll version in the file names and not just inside the file.

On windows, an app can install a DLL/lib not part of the application
On Linux, an app can't install something not part of the app but will have a dependancy on it.
the setup manager is part of the os, not provided by the app and will automatically try to install dependancies.
it will also forbid to desinstall a lib used by an application.
I think it's much more powerfull even if this require to not have everything packaged in the app installer.

Google (so youtube) recently bought the codec company, which codec they used.
so they are in a position which allow them to open up this codec (or a new codec ?), which would make one more open codec available.

Yes, you can offer multiple format. You nevertheless need to have both file ready on the server side...

You can install locally a linux dvdrom (or repository copy)
that would make your install working without having Internet.

BTW, on Windows, I remenber having Office and Windows asking for network installation disk. If you didn't copy the installation disk locally, you've got the same kind of problem. (this is why most people select install everything to avoid being popuped while typing something into word because the software suddenly tries to install a language pack which you don't use...)

You obtain a lesser memory print on Linux by sharing libraries, which is more difficult on Windows, especially for non microsoft software.

You're assuming wrong. You've got a restricted licence included with Windows. If you're out of the licence scope, you need to buy another licence ! For example, if you produce your videos, you can be very quickly out of the licence scope.

humm, both IE8 and Firefox 3.1 will include a private browsing feature but neither have "shipped".
But you're right that IE included it before in a beta and that increased the priority on the firefox people...
Time will say which of these version ship the first (in a non beta, non rc mode)

I find it funny that openoffice is in the situation mozilla was some years ago...
- big code which takes time to clean up (There was some presentation made by an openoffice guy which explained all the work they have been doing to remove old code, factorize code, clean up...)
- mostly contributors from one company, slow to gain external contributors
- hard for external contributors as some stuff are naturally "inside"
- patches sitting and not being integrated
- need to release stuff and at the same time work on more architectural stuff
- work needed on tools to ease distributed contribution and extension stuff

the only difference is that as a product openoffice.org 3.0 is much more a success than early mozilla version so that should help drive developpers overcome the other problems...

I think some of the above problems seems to have been partly adressed but as the number of sun developpers decrease, it complicate integration of needed new developpers...