[Kalimac]

I was always under the impression that Gollum could get in *just barely* - that is, he could skirt the edges and maybe venture in a little ways, but he wouldn't enjoy it and certainly wouldn't camp out there for preference. Probably he just skulked around the borders waiting for the travellers to depart so he could follow them down the river.

It's not surprising that he'd be able to do this much, when we consider that Orcs were able to approach the edge of Lorien as well (granted, they didn't get very far, but still). Again, they doubtless hated the place but could probably skirt it if they had to - that is, if Haldir and his merry men hadn't taken care of them first.

Probably this has to do with relative degrees of strength, like a lot of other power-related stuff in the story. Gollum and the Orcs, while nasty, are pretty low on Sauron's food chain - they can't really do much by themselves, so they aren't as knocked down by the power of Lothlorien as, say, someone like the Mouth of Sauron probably would be. It's a parallel to the situation on the other side where Gandalf is readier to trust the comparatively-weak Frodo with carrying the evil Ring, while he himself is afraid to even touch it because he's so much stronger for good, and therefore will have a much more drastic reaction to it.