To setting the focus of an input field in jquery, it was simple. But when you have a peoplepicker field
you think that you also are dealing with an input field, but less is true. A sharepoint People Picker field isn't that easy made. But we won't be a developer, if we could make a function that put's the focus also on a people picker field. Below you find my function. It can be extended with other fields if necessary. You call it not by using the GUID, but by using the display name. Which is more flexible and easier, because you don't need to search for the GUID in the source code. You can call it by the next function. You only need the Field Display Name and the Type of field. The type can be at this moment, an Input field, a People Picker, or a Select field.
This you can use by example when you want to check values in the PreSaveAction function and you want to put the focus on a field that has to be changed.
Have fun with it... and if you need an extention, don't hesitate to ask...