I just jailbroke my iPad, and the only tweaks I have installed are PasswordPilot (my reason for jb'ing) and Springtomize 3. With Springtomize on and set for a 7-icon dock (same as on my 7.1 jb), my dock will only let me add 6 icons, and it's shifted to the left in both portrait and landscape mode. Turning Springtomize off restores the normal dock.