Google Nexus One 3G issue will not be fixed via software update23
Okay, let's try it one more time, just in case. Switching the Nexus One's orientation... nope... going to the other room... nope, still no solid 3G signal. Well, it doesn't work.
Here's the complete post by the Google employee - don't hate the messenger, he's just doing his job:
I've seen some recent speculation on this thread about an OTA to improve 3G connectivity and I want to give you an update on the situation.
While we are continuing to monitor user feedback regarding the 3G performance on the Nexus One, we are no longer investigating further engineering improvements at this time.
If you are still experiencing 3G issues, we recommend that you try changing your location or even the orientation of your phone, as this may help in areas with weaker coverage.
Google Nexus One Specifications | Review
source: Google Support Forums