I haven't had to do this myself yet but i think this is something I would be interested in having as well. The only way I could think to do it would be to create another table with the values you want to report on. I'm not comfortable with my ability to do this efficiently so take that into consideration and this is not entirely thought out yet.
1. Create a table(lets call it R for report) with the values you want from other tables with a old and new column. On initial creation fill the old and new column with the same data.
2. On whatever interval you want update table R's new column with data from the tables you used to create table R. But only update the New column so we can use that to compare with the old column.
3. Then you can report on this table looking for any Node where the New and Old Column do not match.
Please tear this idea apart so it can be better and we might get something of value out of it. Hope this helps.