I've created a proposal here http://maemo.org/community/brainstor...op_separators/ to add support for Separators on the desktop, similar to what you'd see on the S60 desktop.

This would help to group icons or widgets.

Thanks, but can you add some screenshots, maybe of S60? I'm not familiar with what you're proposing.

yes please provide some examples, I have no clue what you mean with separators...

Apologies if I wasn't making myself understood.
I've attached a quick image to illustrate

Resizable screen dividers to group icons or widgets.

OK. And would these dividers just be things that you draw on the screen for neatness, or would they actually do something? I mean, if I dragged the horizontal divider down in your mockup, would that move the calendar widget and the shortcuts widgets on the left and right down too?

you can already neatly arrange and snap icons to a grid using tweaker... so are they needed?

It'd be nothing more than an an image file placed where you want it, stretched or shrunk horizontally or vertically. Probably more decorative than anything but it can add to the neatness of a desktop.
The example I provided was rough, just a very quick edit in gimp. If needed I'll make a better example when I get home

A long time ago I created a wallpaper with similar 'separators' (areas with different colors on top of a nature image) for my desktop. This indeed helped grouping items on the desk, but I'd say the N900's screen is too small for an additional grouping. In fact: what is the benefit of the example shown? The items are already grouped and there is not much space left.
Nevertheless you can create backround images with colors or lines that help you grouping items. I'd presonally prefer more virtual desktops (screens) with an improved way of switching between them.