Just read this at Xboxyde from 360 dev Deftangel re: the update, take with a grain of salt
"Oh and by the way, although the Spring Dashboard update isn't going up right now, I don't expect it to be very long in the works...
It definitely has background downloading, and it's quite tidily done IMO.
Also remember a lot of people asking Major Nelson why you couldn't set your 360 to boot straight to dash when a game was in? Well now you can :-)
You'll also be able to keep your own music playing when changing games.
Lots of other tweaks they've made to the Dash and the Guide by the sounds of it :-) It makes sense to get this out by next week for E3 obviously but as we go on, the longer it takes to release Dash updates as there's simply more stuff to test, not least for anybody releasing any games between now and when it ships. Watch this space :D"
Sounds good, hope it happens before E3