Camelot looks to become a very powerful and musician-minded performance environment, and I'm really excited to see it grow. But as AM likes to point out, it's still in its infancy as new features are being added. One of the big caveats is the lack support for AU/VST effects.
However, there is a pretty good solution that will run you between $50-$100 depending on your needs. There are a number of plugins out there that serve as AU/VST hosts. They appear as Virtual Instruments that load into any Camelot layer, but inside you can load an instrument and multiple effects chains. Here are three:
DDFM Metaplugin ($40) is the cheapest and newest, but it seems to work great and has a decent demo. I'm trying it out now and it does the job.
Plogue Bidule ($100) is a crazy old Canadian warhorse with similar patch routing to Metaplugin. It's an amazing plugin if you want to do more advanced modular programming like Reaktor or Max/MSP.
BlueCat Patchwork ($100) is the most slick with a very user-friendly interface designed for complex rigging. I've never used it but BlueCat is a great outfit and I'm sure it's stellar.
Considering AM plans to add effects support in the fall, I'm probably going to go with the cheapest option... though I've been eyeballing Plogue for years for other purposes, so maybe I'll swing that way. My only problem with Plogue is that they don't have a demo of their plugin, only standalone app, and I really want to see how it performs inside a host first.