Hey folks,
Don't know if you've solved this problem or not. I had this issue with my Epic Touch. Here are the steps ( I can only talk abut Epic Touch):
1. When someone send you vcard via sms, you open it as a video file. While it's playing it, click on menu, then click on Attached item.
2. Check the box and save the vcard to download. You should see a message saying "Attachment saved to your SD card"
3. You need an app such as ASTRO from the Market.
4. Open the app ASTRO, and scroll down to the folder "Download", you should be able to see your "vcard".
5. Click on Vcard, a window pops up and ask you "Complete action using: Contacts, File Editor, etc"
Good luck,