1) You can read a photocell directly from a PC without an Arduino. The PC serial port and a couple of passive components can be used as a simple analog-to-digital converter for a cost of pennies. One of many examples can be found here: http://www.cedarlakeinstruments.com/blog/archives/10
2) Similar idea using a Beaglebone or Raspberry Pi would eliminate the Mac/PC for a more compact solution.
Those aren't simplifications. Those are optimizations. They actually require more hardware and technical know how than the original.
This article is a fantastic little recipe for what might be the easiest path to a first IoT project. It puts the maker in a perfect position to go on to add a second sensor or switch and further experiment. There needs to be much more of this type of thing on the web. Props to the author for writing this up.
Cleverly optimizing out the arduino or adding a fancy SBC to the mix are great suggestions. After you've got the basics.
1) You can read a photocell directly from a PC without an Arduino. The PC serial port and a couple of passive components can be used as a simple analog-to-digital converter for a cost of pennies. One of many examples can be found here: http://www.cedarlakeinstruments.com/blog/archives/10
2) Similar idea using a Beaglebone or Raspberry Pi would eliminate the Mac/PC for a more compact solution.