Update: DroidMatters has a possible no-hack way to stream Netflix on non-supported Android devices.
If you have an unsupported Android phone (or Nook Color!) and want to try Netflix streaming, Reddit user Natemckn posted a possible hack that involves rooting your phone. It doesn't work for everyone, and if you don't feel comfortable
Warning: You're doing this at your own risk. Be sure to make a backup and understand that by doing this you might brick your phone (HackingNetflix cannot repair your phone for you).
Here are the instructions:
0) Root is required. Make a Nandroid backup! (I accidentally deleted by build.prop file and bootlooped my phone)
1) Download ES File Explorer (Or any other root file editor)
2) In ES File Explorer, go into Setting > Root Settings and enable both check boxes
3) Navigate to /system/ and copy/paste build.prop to /sdcard/ (just in case)
4) Open & edit /system/build.prop
5) Change the following lines to make your phone think it is a HTC G2:
6) Reboot the phone
7) Install the netflix apk (if you haven't already)
I tested this on my LG Optimus V running AOSPCMod v20110427 (Android 2.3.3). Before this, it told me that my device is not supported, now I'm watching 30 Rock episodes over 3G. I did not come up with this, I stole it from some posts on xda and compiled a nice step by step guide. I take no responsibility for screwing up your phone.
Good luck and Enjoy :D
EDIT: updated for less line changes
EDIT2: I guess this is kinda hit or miss, but it does seem like it is working on multiple people's Optimus V's and Nook Colors.
EDIT3: Added the Nexus S settings that worked better for some.