It looks like you are being stung by a version mismatch. The version of gnucash for every architecture but powerpc is 1.8.9-4. However, the version of gnucash-common (for all arches) is 1.8.10-2 . Unless you are using powerpc, there is currently no version of gnucash you can install in the unstable archives.
Here are your options: you can wait and hope the situation sorts itself out. I do not see the version mismatch listed as a bug on the Debian Bug Tracking System, but I am not sure whether this should be reported as a bug or not.
Alternatively, you can use the version of gnucash available in testing. The dependencies there are consistent. To do this you may want to use "apt pinning" to prefer the testing versions of gnucash and gnucash-common. (There may be other ways to do this as well. I don't know of the details for any of these, but the APT HOWTO document should help.)
Last edited by pnijjar; 01-14-2005 at 12:02 PM.