Apparently not. :)
Here's a quick rundown of my initial impressions:
I found it very easy to get Chipmunk up and running. It's new so the plugin library is a bit on the thin side compared to an old-timer like Girder, but I found the plugin selection adequate for my needs (mostly, as I'll explain momentarily). The currently available plugs provide USB-UIRT support, RS232 support (send and receive), an on-screen display plugin, a fairly flexible event scheduler, and an integration plugin for Chipmunk's own software "remote control" applications.
At first glance, it looks similar to Girder: you have group folders, macro commands, script commands, and events all arranged in a collapsible tree structure. However the similarities are mostly cursory, and as I mentioned earlier, the tree does not represent any Boolean relationships (and/or/not).
One thing I immediately missed from Girder was the ability to control Windows applications. Chipmunk didn't have this. My main concern was distributing IR signals and RS232 control of matrix switchers, but I liked the idea of remotely controlling Winamp, PowerDVD, and similar apps on the PC in the AV closet. At first, I was ready to dismiss Chipmunk, as this appeared to be a major shortcoming. However, I've been a programmer my whole life, and I did notice Chipmunk offers an SDK, so I decided to have a peek before I turned my back on it. It turns out the SDK (which is the actual code used for the OSD plugin) is very easy to use for anyone versed in C# .NET programming, which I am, so I said what the heck: I rolled up my sleeves and wrote a plugin today which lets the program issue low-level Win32 window messages to other applications (with several extra features, such as starting the app if it isn't already loaded, timing control, and the ability to force the target app to the foreground). Since everything in Windows operates on the basis of these messages, in theory you can control just about any application.
I haven't "officially" released the plugin yet (I only finished it a few hours ago), but it will be available very soon (within days), free of charge, hopefully on the Chipmunk website. This plug-in makes it possible to control Winamp, dscaler, PowerDVD, or whatever other windows apps you need to operate remotely. So with that, Chipmunk can now handle every task I had envisioned using Girder for, but with far less setup hassle.
I also liked the fact that Chipmunk saves your settings in files in locations that you choose, and all the files are in plain-text format (the Lua files are just text, and everything else is XML -- mostly .NET serialization output, but simple enough that someone could conceivably edit them by hand if necessary, and they're very readable).
I also like that it can *learn* (not just read) incoming serial port traffic and respond to it as an event. I'm not sure whether Girder can do this -- getting started in Girder took so long, I never got around to working with the serial ports, but I don't remember seeing anything about it.
Chipmunk doesn't really have the concept of a pre-configured remote which exists in Girder. Since I'm doing a lot of custom stuff with a bunch of Philips Prontos, I'm not sure this matters much to me. In any case, I was very dissatisfied with the inflexible approach to remotes in Girder, so I can't say I'll miss it much. However, I can imagine some beneficial scenarios to establishing IR remote profiles.
Speaking of remotes, one of the original goals of Chipmunk's developers was to create software "remote controls" for operating AV equipment. Consequently, Chipmunk includes a designer that allows you to draw your own remotes and wire up their events to the hardware you've defined in Chipmunk. These software remotes can also be run on PocketPC devices, or on other computers across the network. It sounds sort of cool, although I haven't messed around with that part yet.
The developers are very responsive, and seem to be putting a lot of work into improving the application. I exchanged e-mails with the main guy several times. They're planning another release that expands on the plugin/Lua-script interactions and improves other plugin functionality, and they have a partnership arrangement with GlobalCache (makers of IP-based automation and IR equipment) and RedRat (a device popular in Europe, similar to the USB-UIRT).
I haven't really loaded the system down yet, but I haven't encountered any bugs at all, and I've been working with it for nearly 20 solid hours over a period of two days.
All in all, if you're not already tied to Girder, I'd recommend giving it a whirl.