(Started by TV)
The title says what I want to ask: is there any at the moment, or stuff I could try to use for a build (without official signing, but I should have the devkit around)?
The machine/phone does live TCP sockets which should be great fun and has a very big screen for a phone (800x352) which could be great for Tk!
MAKR (2008-08-29): As I will soon be the proud(?) owner of a Nokia E71, I looked into the issue too. Although Symbian provides a Porting Guide [L1 ] it became obvious that if you ever want to release something to the public, it is going to cost you real money [L2 ].
Furthermore, setting up a development environment has to be done under Windows. Except if you are willing to cobble something hybrid together, i.e. writing and compiling might work on Linux, but testing needs at least Wine. See here [L3 ] and here [L4 ] for howtos, patches, and toolchains.
Finally a warning, if you are going to sign into Forum Nokia, i.e. to download their IDE or SDKs [L5 ] read the Terms & Conditions very carefully! IANAL, but it seems to me that you will be signing an NDA.
With regard to Symbian OS there is also SonyEricsson with a quite large developer community [L6 ].
I will abuse this page to collect more information...