At the moment we've got Twisted in the main thread, spawning a thread to run wx. It works nicely except we can't figure out how to communicate with wx (ie., generate wxevents) from twisted. (We don't need the converse - it's notification only.)
You just have to call wx.CallAfter, it will let you call any function inside the wx thread. I've put an example of this use online: http://solipsis.netofpeers.net/wiki/WxTwistedExample
It may be better, by the way, to run wx in the main thread and Twisted in the secondary thread. Some toolkits supported by wx may not like the fact that they aren't called from the main thread - I'm not sure such a limitation exists but I'm not sure of the contrary either. Twisted, OTOH, does not seem to care at all.