We're still waiting on a fix for the problem the Nexus One is having staying connected to 3G (and we don't really care who fixes it -- Google, HTC, T-Mobile or whomever). In the meantime, there's a workaround that will force your phone to only connect with 3G.
So join us after the break if that's the sort of thing you're looking for. (With a big tip of the hat to XDA Developers)
OK, big caveat here: This is going to force your phone to only connect over 3G. So unless you're in an area with good T-Mobile 3G coverage, mosey on past. Otherwise ...
Head over to your phone dialer. And just like you see in the picture above, dial *#*#4636#*#* You might not actually see the final asterisk appear, because as soon as you hit it, your phone's going into testing mode.
Don't worry, this isn't anything as serious as rooting, and you're not going to brick your phone. Promise.
OK, now you're in testing mode, and you should see four options. Tap on "Phone information"
Scroll all the way to the bottom of the "Phone information" screen. You should now see what looks like the picture on the left here. Under "Set preferred network type," Tap where it says "GSM only." (Yours may say something different -- I'm on AT&T here.)
Now, change it to "WCDMA only" like you see in the picture on the right. This will set the phone radio to only connect over 3G. Remember: If you're not in a T-Mobile 3G area (which is always the case if, like me, you're using AT&T), you will not be able to get a data connection at all.
By the same token, you can force it to EDGE-only by choosing "GSM only." And, yes, there are some CDMA options. The Nexus One, after all, is coming to Verizon.