Hibernate version:
2

What are implications (such as transactions) if there are multiple sessionfactories for one single database. I have the need to package related hibernate classes with their business services.

Thanks

When You are using a second level cache, You have to choose one with cluster capability. Transactions are handled by JDBC-driver of the the Database. So it should not be any concern as long You are using the same database. The clustered cache means a significant overhead (especialy when threads are on different machines), so I used a JMS-based cache to do the synchronization asynchronly. (This means definitly that You will have some conflicts in favor to performance)
Another concern is the heavy weight of SessionFactories. They need some time to initialize and will use lot of memory. I do not understand Your intend; why You have to package all hibernate classes and what are Your business services? (how many;) )

An other approach would be to have a second level cache per SessionFactory, use <version> for optimistic locking and have an eviction policiy on the second level cache which cleans up lets say every 10 minutes or what ever is suitable for you.

HTH
Ernst