I'm having memory leak problems myself, but I'm not 100% certain that it's a leak yet.
Here's a question for you. Are they actually leaking, or just using a lot of memory? His log shows you the number of objects of a specific type. For example
Top 20 +50: String (29871) +1: Hash (1128) +1: Time (40) -1: Proc (512) -5: Array (1048)
This means that the number of strings since the last logging has increased by +50 and the total number of strings are 29871.