This is possible.
Define 3 regions in the page.
You can provide a select List Item in Region 1, and allow user to select an option. <region 1> <region 2>
Region 1 ->Conditions ->Request = Expression 1->Under Expression 1 -> Define the value you gave for region 1
Region 2 ->Conditions ->Request = Expression 1->Under Expression 1 -> Define the value you gave for region 2
You need to set the regions you want to be included in a display selector by setting that attribute to Yes in the attributes section of the region definition, then create a region of type 'Region Display Selector' (the last option on the list when creating a region). You can do this in 4.0.2 anyway. Or were you asking if you can have more than one selector on the screen?
I don't think you can have multiple region display selectors out of the box. Maybe other forum uses know of a way.
You could do this with Suzi's suggestion of a selection list or radio set, but using dynamic actions (instead of a submit and region conditions) to hide/show entire regions on change of the selection list/radio set value.
I tried the steps documented in http://apexplained.wordpress.com/2012/07/16/hide-the-show-all-tab-in-a-region-selector/#comment-228. All worked well except the last jquery code:
It would only work if the Region Display Selector is a sub-region of another region as done by the author. Otherwise, it won't work. Here is the more general jquery code that you need to insert to the page's "Execute when Page Loads" section.
// The following jquery code disable the "Show All" link in Region Display Selector (RDS).
// Remove the "Show All" link from the DOM.
// Assign the next link to be the first and selected link.
// Click the first link.
$('.apex-rds > li:eq(0) > a').trigger('click');