Quick recap what Oracle XE is;
Small footprint Oracle database, RPM based installation, almost all the features of Oracle SE, does lack the JDK, comes with Application Express (formaly HTMLDB) pre-packaged and ready to use.
However limited to the use of 1 CPU, 1 Gb memory and 4Gb user tablespace.
Just installed it on my Fedora Core 4 workstation at work, works perfectly so far.
There is also an XE client rpm available, lets hope they package up the instant client as an RPM as well.
Oracle XE doesn't have os auth enabled by default, to allow the use of the normal ops$ users issue this command in sqlplus
alter system set os_authent_prefix=ops$ scope=spfile;