Ever since the HSDPA switch was flipped in my area of NYC/North Jersey and the backbone was improved, my Nexus One has no longer been fluctuating between 3G and EDGE. I also noticed a speed increase in general. Funny thing is now in the rural and indoor areas where it was happening, I sometimes lose signal altogether, instead of dropping to a slower mobile state. Now, in the past, whenever towers in my area have underwent an upgrade, I noticed my signal was less than stellar for a few weeks while the process was flushed out, so that may be what's happening or it may not. Has this happened to anyone else and their Nexus?