what am i doing wrong with tha *tar.gz-files from garage.maemo.org? they're the only ones I cannot open (none of them), neither with gui-tools like the file roller nor directly from the command line. - anything special about them? (yes, i know this is mot maemo.org, but its so much easier to communicate here…)

benny1967,
I notice the same yesterday when made patched maemo-mapper 2.0 package. Not sure about all *tar.gz, but one from mmapper download gzipped twice. The only way to get it open :
gunzip *tar.gz and you get proper tar.gz file. The rest is as normal.
Hope this help.

worked. thanks!