@MrN: Please keep us posted if it works. Apparently many users claim DITS Phonebook to be a big scam... lets hope its not cuz I really need to order one soon & get my iphone activated before i jb & unlock it.

Are you stuck on the 'Emergency Calls' screen on the iphone?
If yes, then you will need the original carrier's simcard or a phonebook simcard to get past the 'Emergency Calls' screen & to the Home Screen. [It's called activating your iphone before you jailbreak+unlock it]
If no, then try restoring OS 4.0.1 via itunes again.

Yes you can still jailbreak+unlock your 3GS provided you are able to ACTIVATE the iphone once you update your firmware to 4.0.1.

In order to activate your iphone you will need the original carrier's sim card or a phonebook sim card.
If you can't get your hands on either of the sims then I would suggest you to not updagrade your firmware till a hacktivation software is out [eg. Pwnage Tool/sno0wbreeze/redsn0w]

@rajshan:

Yes... Unlock+Jailbreak possible.
Hope you already have an ACTIVATED [meaning you can access the home screen] iphone on firmware 4.0 or 4.0.1
Once your phone is activated, connect to jailbreakme.com through your iphone's safari web browser [wireless connection required]... Follow the instructions & you'll have Cydia on your Home screen
Next, open Cydiia, add the source [repo666.ultrasn0w.com] & download ultrasn0w 1.0-1 from the packages & you'll have an unlocked & jailbroken iphone.

Did you try restoring you last back-up on your iphone via itunes & a reboot after that? That might help. Hope you took a back-up of all your data before unlocking/jailbreaking your iphone 4.

Hey there ppl... I have an iPhone 3GS
1. Old Bootrom [iBoot 359.3] mid-sept 2009 model
2. Jailbroken & unlocked on 3.1.2 with earlier version of pwnage tool
3. No SHSH Blobs stored for 3.1.2/3.1.3 :(
4. Model: MC135LL

I somewhere read that pwnage tool 4.01 does not work for MC models of 3GS. Is that true? (the Pwnage Tool 4.01 info doesn't mention anything about MC/non-MC compatibility under the 3GS section)
I just have one shot at this. I don't want to mess this up. I can't use 'jailbreakme' cuz I won't be able to activate my phone once I restore to the official iOS4.0.1... Am living outside of the United States... unfortunately no AT&T or Phonebook SIMs are available in my country :(

Hey there... thanks for this JB release :)
Can anyone please help... I have a 3GS old bootrom on 3.1.2. How do I activate my 3GS when restored to official OS4? I don't think I'll be able to move on with the jailbreaking via safari unless I activate it...
The phonebook SIM cards are not available in my country...