[Plugin: Jetpack by WordPress.com] Settings page breaks WP's dynamic menus

When I go to the Jetpack’s settings page at /wp-admin/admin.php?page=jetpack, all the menus on the left stop being dynamic: I cannot open the submenus by clicking on the down-arrow. In fact, the only submenu open is Jetpack’s.

I’m forced to click on the submenu headers to be able to see what’s in the submenu.

It looks like Jetpack is disabling the Javascript in the Admin page.
This is what I get in the JS console:
TypeError: Result of expression 'jQuery.now' [undefined] is not a function.

I’m running WordPress 3.0.5 in a multisite.