Formatting is stored in:

/System/Library/Frameworks/AddressBookUI.framework/ABPhoneFormats.plist

Download this file from your phone. The file is stored in binary format, so you'll need to convert it to text. Now save this file and open it in a text editor. Change the formatting under us to look like you want (if you find your region in the file, just copy from your region to the us). There's probably some way to just make it use your language (instead of 'us'), but i don't know where you specify that. When you are done changing formatting, save the file and upload it to the iphone in same directory you found it. You don't need to convert i back to binary.

Update for 1.1.1 users: In previous versions locale settings did not apply to number formatting. I noticed that in 1.1.1 it does, so it's better to change the phone's locale configuration instead of changing the formatting manually. Install "Enable International Menu" found in the Unlocking Tools category.
Making the carrier name/logo fit without scrolling

Apple left a rather small space for operator name, so if it's above 7(?) characters, it will scroll, and display only first part (click picture at right). I found a way to decrease the font size, making it fit.

Load the following file in a Hex editor:

System/Library/CoreServices/SpringBoard.app/SpringBoard

Font size should be at offset 7C176. In HxD, just click "Search → Goto" and set offset to 7C176 as shown in picture below. If the font size is not at this offset in your file, you can try a text string search for loopOperatorToBeginning, it should be right above that.
99603 98989

As you can see, you can also change the font type, and color of the text. Default is size 14. Changing it to 11 or 12 should do.

Update: Here is a way to set a permanent carrier logo. I have created a few logos for norwegian users (screenshot below): Telenor, Netcom, Tele2, Chess, OneCall. Download here. Remember that you will need to change pictures manually if you switch carrier.
104802
Disabling autocorrection when typing on keyboard

Read here until i write a more detailed way.
Adding international characters on the keyboard?

Read here until i write a more detailed way.
Unlock.no's version of jailbreakme.com

I've studied how jailbreakme.com jailbreaks the phone etc, and i noticed that jailbreakme.com copies a 736KB archive with the needed files (136KB), but the other 600KB is just CRAP (hidden mac files, sourcecode etc). So i decided to tweak the solution a little.

* I have removed all the "crap" jailbreakeme.com serves, so my archive is only 136KB, but still have ALL relevant files. This will make it much faster and more stable, since the file transfer is reduced by 600KB!
* Latest version of Installer (b10) is installed, and also latest version of Community Sources (modmyifone repository) - i will try to keep these packages updated at all times, so that you don't need to update anything after jailbreaking.
* http://i.unlock.no/ is addded as a (trusted) source in Installer, so that you have quick access to common tools like "Baseband downgrader" (reflashing baseband to 1.0.2 baseband) and "bootloader downgrade" package (Unlocking Tools category).

To jailbreak using this method, instead of adding URL jailbreakme.com, you add url: i.unlock.no (http:// not necessary) to the contact you create after dialing *#301# etc. Have your phone docked to the computer when visiting the jailbreak page! I have no idea why, but sometimes it doesn't work if your phone is not docked (this applies to jailbreakme.com as well).

Note: Jailbreaking using this method will add i.unlock.no as a trusted source. If you don't trust this Installer source, don't do this.

I did not develope this solution myself. I use jailbreakme.com's solution, and just tweaked it. All credits/donations goes to everyone who worked on this solution: http://jailbreakme.com