Both are definitely locks to be on the All-Star team at this point. Starting, that is another matter.
KG's biggest opposition will be Bosh and Stoudemire. KG's name still carries a lot of weight with fans, but enough to ovecome the hype from Miami, I'm not sure. If the vote was up to coaches, KG wins hands down. The fans may see things differently though. Plying next to LeBron and Wade will get Bosh a lot of votes. Stoudemire plays in NY, and that is a pretty big market, with a lot of visiblity.
As for Rondo, Rose will be his biggest opposition. Rose scores more points, has flashier highlights, and seems to be hyped a little more by the media. Rondo has been getting his fair share of media attention lately though, so it will be interesting to see who is more popular with the fans. Rondo (the better player) or Rose (the more hyped player).