Are there any Python alternatives similar to Esper (Java and .NET) that deal with complex event processing (CEP)?
Casual browsing indicates that this is not a very common problem domain for Python (although very interesting!). The framework that closest come to my mind is PEAK-Rules or dynrules.
There might be more, but not widely known (I'll search a bit more)
For your own digging: the place to find Python projects is first and foremost PyPI.
(@cues7a: Twisted, while indeed being an event framework, is too low-level to be comparable to Esper.)
Edit: It seems you can control Sybase's CEP products with Python