I'm seeing this bug on OS X 10.8.2 (64-bit) with NetBeans IDE 7.2.1 and "Java: 1.7.0_10; Java HotSpot(TM) 64-Bit Server VM 23.6-b04".

While the bug appears in other more common situations (not involving a minimized window), the following is the most reliable series of steps I could find to produce it:
1) Open a Safari window (any other process should work, it seems). Minimize it using the yellow traffic light in the upper left-hand corner of the window. Safari is still the selected process (as evidenced by the Safari menu bar), but without any windows open.
2) Open NetBeans IDE with an editor open. Move the mouse cursor in the editor so that the mouse cursor changes to a caret-style text cursor.
3) Without moving the mouse, press Command+Tab to switch to the Safari process (which doesn't have any open windows at the time). The mouse cursor goes back to the default pointer cursor.
4) Again without moving the mouse, press Command+Tab again to switch back to the NetBeans IDE process and window. Even though the mouse is now again hovering over the editor, the cursor is still the default pointer cursor instead of the caret-style text cursor. The cursor will only return to the text cursor if it is moved out of the editor and back again.

This seems to be a JRE bug, as I can reproduce the same problem in a simpler Swing app with a cursor with a custom component assigned to it. I'm filing it here as there might be workarounds possible from the NetBeans Platform side, however. (E.g. maybe the cursor could be forcibly refreshed whenever a NetBeans window is brought to the foreground.)