[mcgowanbl]

This works with standard $15/month Sprint PCS Vision plan.
No you do not need to purchase Phone As Modem plan.
No they will not charge you extra because there's no way for them to known you tethering to a pc.

I have two Touch Diamonds (not Pro's).
One for my wife and one for me.

My Internet sharing (Start\Programs\Internet sharing) only has one drop down menu, "PC Connection".
My wife's has two drop downs "PC Connection" AND "Network connection".

Now I bought her's two days after mine at the same Sprint store.

Her Internet connection shares Internet via USB connected directly to a PC without issue.
Mine doesn't since I have not been able to set the missing "Network connection" drop down menu option to the appropriate setting of "Sprint". Instead it either say Waiting for network or error 67 invalid username and password (something like that)

I deleted the key: (not just the value)
[HKEY_LOCAL_MACHINE\Comm\InternetSharing\settings]
ForceCellConnection

Now I got the second drop down menu "Network connection", restarted the phone and now it works like a champ.