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Finally the Update has arrived, sony kept their word. 
i am updating now
Install flashtool from this link.
After you install it take two-three biggest files from SUS directory (not PCC)
they are located in SUS directory/db/"some big number"/blob_fs/
If you updated phone more times they will be more them so just take newest ones.
tutorial for creating ftf file
I want to wait a while with the update :smileygrin:
After you done that open flashtool and go to advanced>decrypt files
then navigate to directory where you put those files and click ok
then move all files frol left to right and again click ok
Flashtool will extract sin files
Then go to flashtool>advanced>bundle creation
Navigate to folder in with are sin files.
Move all files from left to right but not simlock.ta
Fill device, version and branding info and click ok.
FTF file will appear in C:\Flashtool\firmwares\
Lucky you guys. Just let us know how it works and what do you think about it, bad things good things. The updates are after the countries and operators so if you mix-up the updates between countries could be bad for the phone. Sony should explain this if it is or isn't right.
Yeah, that's what I thought.
If I create the FTF file from my O2 CZ firmware, will others be able use it on their non-O2 CZ phones without any problems?
I have connected my collegues XU from T-mobile CZ to my computer and it says that there are no updates available for him 
OK, seems that I was successfull with the FTF file creation, it's size is about 500MB.
I'm just trying to figure out where should I upload it 
Uplodaded here:
http://uloz.to/xL9rEpX/st25i-6-0-b-3-184-o2-cz-ftf
I have followed the instructions above and didn't experience any problem with the FTF creation, but please note that I cannot guarantee it's functionality, you will be responsible for possible bricking your device 
Thanks but first I got 162 update nofication,then I updated and there wasnt new update,after six hours passed I got 184 update.
Update is taking too much time... is it due to busy server?? I think all Xperia U's are started updating 