We have a completely free implementation of JSR 114 on Sourceforge (search Ross Group Rowset). It is a derivative work on Sun's reference implementation. We will be maintaining this version for the foreseeable future. We created this project due to issues with the reference implementation and what we perceived to be misinterpretations by Sun of the specification. Also, the reference implementation does not provide the full feature set defined in the spec.
What we've done so far:
1 - Allow insertRow() even if not all "not null" columns have values.
2 - Added an "addColumn" method so you can dynamically add columns to an existing CachedRowSet. Also, these are added as "read only" so they are NOT persisted back to the data store.
3 - Several performance improvements, particularly in String handling. Seems the guys who wrote Sun's implementation love to use str1 += " more memory allocations".
Coming very soon (later this week):
1 - Support for setReadOnly() on columns, and respecting that in updates and inserts.
2 - Proper implementation of undoUpdate, undoDelete, and undoInsert.
Again, this is completely free, distribute it how you want, we don't want anything from you except feedback.