also check out the @Lob JPA annotation:
A Lob annotation specifies that a persistent property or field should be persisted as a large object to a database-supported large object type. Portable applications should use the Lob annotation when mapping to a database Lob type. The Lob annotation may be used in conjunction with the Basic annotation. A Lob may be either a binary or character type. The Lob type is inferred from the type of the persistent field or property, and except for string and character-based types defaults to Blob.
Nice, and does it work well with lists too?
I don't know, I have yet to actually try this. Interesting problem you brought up. I believe the Bauer/King book briefly covers @Lob.
I wonder if any of the Seam distro apps save GIFs, JPEGs, etc. to HSQLDB (if HSQLDB can accommodate LOBs)?