Great news, everyone!
I have Social Beat (a Facebook/Gmail/Twiiter/MySpace/more application) working on the enV touch for free! You'll obviously need a data plan (or risk incurring charges), but the download is from Verizon, and works with minimal glitches.
Verizon, as you may know, gives away this application for free on many other devices- but the enV touch is 'incompatible'. In order to download the app, all we have to do is trick Verizon's app store into believing we have a compatible device.
We'll use the service menu to do this, so the usual disclaimer applies: I'm not responsible for anything you break. It's all on your shoulders.
1) Enter the service menu, by dialing ##PROGRAM11000 and hitting send.
2) Enter your service code, which is almost always 000000 (six zeroes.)
(Be careful here! Don't change anything except what this guide indicates, unless you really know what you're doing.)
3) Select 'Media Center settings'.
4) Select 'platform ID'.
5) We're going to enter the platform ID for the original enV, so type in only the number 1145.
6) Hit save. Your phone will restart automatically.
Now, go to 'Media Center' and select 'Browse and Download'. The media center will now think your phone is an original enV, so you should be able to find and download Social Beat.
7) (In Media Center, Browse and Download:) Select 'Get New Applications'. Social Beat should be listed amongst the first apps. Download it- it's free!
This should theoretically work for any application the enV Touch won't support.
If you want (and you probably should) to set the platform ID back to the correct value for the enV touch, follow the above instructions, but replace 1145 with 1291, (or your original value if you had something different.)
I've only tested this on V5 firmware, but I don't see any reason why it wouldn't work on the others.
There may be additional platform IDs that support other sets of software; if I run into any others that work I'll post them.
-The touchscreen obviously isn't supported. You can view the program(s) on the external screen, but you'll need to use the internal screen to interact with them.
-The Social Beat application likes to put asterisks before your username and password. Don't delete these until after you've entered the first letter of your password, or they'll keep coming back.