Yes, Hibernate supports JDBC compliant LOBs. Unfortunately, while Oracle is probably the best overall RDBMS out there, its JDBC support is (shall we say) lacking. I have worked with all Oracle releases up through the latest 8i versions, but have not played with 9i at all so some of these shortcomings may have changed in those 9i releases. A lot of the shortcomings dealt with the way things were implemented on the server itself (like non-scrollable cursors and LOB support), while others were just silliness (like saying they support the XOpen sql extension functions when they really do not).
Because of this "non-standard" approach to LOBs, you need to handle CLOBS and BLOBS differently if using Oracle. Unfortunately, thats just a fact of using Oracle. Check the url below for more info.
http://www.hibernate.org/56.html