This quite annoys me because I sometimes repackage apps and having the .nsi file was a lot more than handy.No, unfortunately I just had to change over to using the current NSIS extraction support in 7-Zip. It dropped the ability to create an .nsi file, but to be honest the files that were created by 4.40 really weren't that useful anyway. I tried to use them as reference a few times to figure out what an installer is doing, and it's just a major pain in the rear to try to read through and follow. I'd still like to have the feature there if it was possible, but I don't feel it's worth a lot of extra effort to bring it back.
I'm wondering how will you manage nsis installer in the future since all dll files have been merged in the same on and therefore it won't be possible to use 7zip 4.40's nsis.dll with newer release.
Will you compile your own modifier version of 7zip?
One solution would be to find whether the file is a NSIS file and use a different version of 7zip to extract it but that's not very sexy.
I'll try to mod 7zip and provide a version which is able to extract .nsi files.
Btw, unshield compiles under mingw and with default optimizations, it takes 109+47.8KB (dll+main executable). With size optimizations, it takes 100+45.8KB. Not that bad. =)