I get asked about this a lot – I know Tim Ricks has a workaround that uses an additional collection which hosts "sections" the user can select and populate, but the ability for clients to re-order project content in a basic sense would be so useful (on a per-project basis).

We work with a lot of architects etc. and it's really important to them to be able to define how their image lockups/videos order themselves on the page depending on the project – at the moment all we can do is give them loads of options and put conditional visibility on any items that aren't used. But it's not exact and it's messy in the CMS.