Forgive me for being vague when I ask this, but I came upon a dummy cake site that was mentioned on here in the past and noticed that they are patent pending. I'm not sure if they are patenting their rental process or the dummy part. Has anybody seen this or have any thoughts on how this is going to effect us (if at all) in general the next time we make a dummy cake for a customer?

My best guess is that they are patenting the way they make the dummies themselves. That is, the process they use to make them. For example, maybe the use a different base than the usual type of foam, or they use a different type of "icing", or whatever.

You can patent a process/physical item, not an entire category of thing. I can patent my process for making ink, or even the fantastic fountain pens that I make, but I can't patent the entire concept of a fountain pen. That concept predates my specific creation, and even if it didn't, all somebody would have to do is make their pen operate in a different way than mine.