Martin, on Ubuntu 6.06 Dapper, I compiled the nsoracle CVS head, which built fine out of the box. It seems to work with OpenACS, but I have not yet used it heavily. I don't think I ever tried the changes above to get the older nsoracle 2.7 release to build against 10g.
I don't now what "oracle-xe" is exactly, is that some 3rd party Debian or Ubuntu package for Oracle Express Edition? Do you know for a fact that it is supposed to provide the same libraries that you get with the normal Oracle 10g server?