...now that i got an cvs.apache.org account i'd need some help with uploading the ssh key.
I also tried to convert my public key file into OpenSSH format, or create a new public/private key pair using ssh-keygen but nothing works. I also tried to generate a new public/private key pair with gpg. That works but there is no private key file generated, which i have to pass to putty/plink.
Do i even have to use gpg?
No. GPG/PGP is for encrypting/signing files and mails. There are currently three widely used public key schemes: GPG/PGP/OpenPGP, X.509 (certificates) and SSH, each using its own format for storing keys and associated information. Confused?
Or do i just have to copy the public key file into a directory?
Yes. It depends on whether you generated a DSA or a RSA key. I got a DSA key and uploaded it into the _file_ ~/.ssh/authorized_keys2 (the name is important and different from the filename used by ssh-keygen, on purpose, you can use multiple public keys by concatenating them into this file) The .ssh directory and the file should be world readable.
Do a web search on "ssh keygen", there are a few tutorials. I got mine working this way, after nearly biting bits off my keyboard.