QT is the Linux Graphical layer equivalent to GTK (which does have more applications).

Qtopia is the Desktop GUI / Applications framework. Ordinary X based desktops simply are not usable on small screens (320x240) etc.

In theory you could have Nokia Series 60 or UIQ on Linux and Qtopia on Symbian.

SDL is another cross platform Linux graphics layer. Tends to be popular for games development.

You can have QT, GTK and / or SDL all under Gnome on Linux or on Explorer Desktop on Windows. They all have cross platform support.

The biggest issues for all devices smaller than 5" 800x480 approx is the GUI/Desktop and Browser. Conventional desktop Windowing concepts and browsers are rubbish on a small screen.

recent versions of Qtopia are more finger orientated rather than Windows like stylus operated. Nicer on a tiny screen, less functional on a 3.5" screen

Broadcom should bugger off unless they can provide Linux drivers for all of their hardware, their wifi and some bluetooth products simply take the piss! They don't release tech specs and they won't release decent drivers.

For instance http://bcm43xx.berlios.de/