A long time ago, Blizzard was toying around with the idea to have two specs that you can easily switch back and forth. Well, while responding to a forum post about the bloat of the WoTLK druid Balance tree, Blizzard poster Ghostcrawler confirmed that this feature will indeed be implemented but we'll still have to wait for the upcoming Blizzcon (October 10-11) to know the details.
Being able to switch back and forth between two specs (for free is what we're assuming or else there's nothing new) is something that will help everybody but especially the hybrids who change roles all the time. You can be a balance druid one moment and a resto druid a little later. This feature will really complement the spell power gear change since the affected classes won't even need to change their gear to switch between healing and dps. Your healer has to go and you only have dps classes in your guild currently online? That shadow priest can go switch specs and heal for you. This feature will also help players switch from a PvE spec to a PvP spec anytime they need to and without the pain of spending lots of gold for respec costs and having to do dailies just to recover the cost.
My guess is that you'll still have to see your trainer to avail of this feature since switching specs anywhere just seems too easy. You'll probably be asked by the trainer if you want to "save" your current spec so that you can switch back to it with ease when you eventually spec out of it.
Whatever the details, this feature should give you that feeling like you're in the Wrath beta spending one copper for respecs. Sure it's not the same but being able to switch between two specs with ease at no cost sure is close.