After being fed up with 4.0 on my 3G, I downgraded the firmware back to 3.1.3. iOS 4.0.1 was supposed to fix the performance issues on the 3G but I wasn't so sure. So, I waited until 4.2.1. Jailbreaking was easy using redsn0w (the part that I always forget to do it upgrade the firmware on my iPhone first then jailbreak).
Now, I'm not one to blog about the newest tech news or anything, but Apple has released iOS 4.0.1 which as they say, "improves the formula used to calculate the appropriate bars for signal strength". Available in iTunes and here. I've always had a cheap plastic case on mine, so I never noticed any reception loss greatly. Although if I do hold it in my left hand for an extended period, I saw 5 bars go to 1 bar.
Firmware 4.0.1 is jailbreakable with the 3G so far, so 3GS and 4 users are out of luck. If the only entry in the change log is the "improved formula", I don't see the need to update personally. Sure, it may say I have 1 bar, but hey, as long as it works.
One of my most favourite apps for my iPhone is iStat. It lets me monitor all my *nix servers in a beautiful interface. For my Linux clients, all I had to do was download the client, extract and compile. And since my router is running pfSense (FreeBSD 7.2) I thought I might as well get iStat on there.
Apparently, the developers edition of pfSense has all the goodies to compile stuff. Without even thinking of cross compiling, I quickly set up a VM of FreeBSD 7.1 (I know little to nothing of FreeBSD so I opted to get something near 7.2) and started to compile it. I had to get libxml2 first though and for FreeBSD 7. Anyway, logged into pfSense via SSH, fetch'd libxml2 and installed it. Now, since my router had nothing to compile packages with, I built iStat in the FreeBSD virtual machine and transfered the resulting mess to pfSense via SFTP. Now, since I couldn't have run make install in pfSense, I had to create /usr/local/etc/istat.conf and filled it in with the configuration file from another Linux client. I also edited the configuration file to fit the network interface (xl0 instead of eth0).
Looking back, I probably could have done things a little different. Either way, I got the job done. Now I'm happy that I can monitor my entire network with one app. I recommend for those that are in need of a functional server monitor to check out iStat for the iPhone. Be warned that iStat only supports one interface so far.
With my iPhone 3G jailbroken with iOS 4.0, lots of other users have been experienced cell phone reception trouble. I tried it myself and covered the left side and saw my signal bars drop by 4. I've read around the internet and its rumoured that 4.01 was supposed to drop today to fix the antenna issues. I'd assume before Friday, there's going to be a fix out there. I, myself, didn't have too much trouble with getting a signal. Where I was reading on Slashdot, it was said that even if the signal is 5% or 100%, you're going to get the same call quality.
I haven't got BiteSMS to work on 4.0 yet, nor five column springboard (fcsb) or Infinidock. A couple Winterboard themes don't work either, such as custom Wifi and signal bar icons. Cycorder doesn't work either. Hopefully, these'll be fixed soon so I can get 4.0 running like I had 3.1.3.
So, after a long time of tinkering I finally got it working.
Get 4.0 (stock 8A293) on your iPhone
Run redsn0w 0.9.5b
Be patient! - This took a bit for me. Once redsn0w says it's done, the screen on your iPhone will display what it's doing (flashing NOR) and a running pineapple(?).
4.0 seems to run faster on my 3G than 3.1.3.
Tried to make this post quick as I'm off to bed!