That's kind of where I see it.
An Arduino Uno costs $30, has 2KB of RAM, and runs at 16 MHz.
The Raspberry Pi costs $35, has 256 MB of RAM, and runs at 700 MHz. It also has two USB ports, ethernet, HDMI, composite video, a great GPU, SD card, and more.
You only get 8 GPIO pins, but you also have I2C and SPI. Plus they were developing a board to help with that.
There are quite a few projects you might want to do that would take quite a bit more horsepower than an Arduino, but a Raspberry Pi would do great for. Think of using something like a Raspberry Pi with a serial breakout board for running a Reprap or Makerbot. Enough power to run the machine and provide an amazing 3D GUI of the object being printed during the process.
It still has less IO than a Beaglebone, but it also costs 1/3rd the price.
I don't think many people will be using the Rasperry Pi to replace netbooks or most desktops, but I see a ton of hobbyist uses.