Refresh my memory, but at what point in the series featured time traveling through the use of the Chaos Emeralds?

They haven't been.

They can 'warp time and space', but not time travel.

The Time Stones really need another appearance. We've got both the Chaos and Sol emeralds now, and apparently they're both going to be part of Sonic 2006... it'd be great if Silver was using the Time Stones to travel through time, but I have the feeling it's just going to be one of his "psychic" powers.

The only other time there was time travelling in a Sonic series game was in Shadow, There were two level set in flashback mode. Lost Impact and The Doom. Plus there was a boss Heavy Dog.

The Little Planet needs to comeback full stop really.

Did'nt Little Planet blow up or something? I remember seeing it do something to that affect in the animated ending.

I believe that was Eggman's...ummm...stuff on Little Planet. lol Haven't played that game in ages not to mention seen the ending(only seen one btw).

It normally exists in another dimension and only visits Mobius/Earth/Sonic-Planet for one month a year. Presumably the "explosion" was the Little Planet returning to its own dimension.

So the chaos emeralds don't have the power of time travel?

No. They don't. They can stop time, make loud explosions, make gods emo, make a damn fine martini and make hedgehogs go super sayian. But they can't go forward or backwards in time.

Lets put it like this after the revelation Shadow was an alien anything in the future is possible.

Also, we can make hot air balloons go up and down, but not side to side or back in time.

I did'nt know that the Little Planey came from another dimension, I thought it was just a floating planet that was destroyed despite Sonic's efforts.

Don't all planets float ?

Shadow being an alien wasn't all that surprising to me, why? It was heavily hinted from the Start of Shadow, and it was a random thing they made up when making Shadow.