It's not as bad as it was, but there are still posters with digs at 4e and/or WotC in their sigs and status lines ("tales from the limited staircase", "gald I'm not a WotC customer" etc.).
Every post these folks make is a mini edition war on its own!
Time for a ban?
As an interesting aside, haven't seen anything of the sort making digs at other editions or games.
Problematic, and unlikely, but perhaps not for the reasons you might think.
One: You pointedly raise an issue with "digs" against 4E (and WotC), but have stated no objection to "digs" against Pathfinder, Paizo, any other system of RPG, or any other publisher of material. Did you mean for your "ban" to only target people who dislike 4th Edition?
Two: People have a right to dislike 4th Edition, 3rd Edition, or any future or past editions. Do I think they have a right to be horribly vocal about 4E *within* the 4E forum? That's basically trolling, so personally I'd say no Do they have a right to express their disdain about 4E in the Pathfinder forum, or the Media Lounge? Well ... sure, why not?
Three: Who exactly shall be the arbiters of what constitutes a "dig" against 4th Edition? Are you nominating yourself? I would like to vote for someone other than you ... so now we disagree about who will get to set this nebulous definition. I'm sure you can imagine the problem if the mods disagree, or Morrus desires not to take a stance at all. Just as an aside: I have absolutely no understand of why 'tales from a limited staircase' would be a dig against anything? The phrase means nothing to me.
Four: As pointed out upthread, you can turn off having to see signatures at all. Certainly a good idea for people, such as yourself, who find them horribly offensive. I'm glad such an option exists.
Five: Why not just ban signatures outright? Wouldn't that solve the problem? Perhaps we should be discussing this instead.
Six: If we establish a precedent of one user's request for a ban on certain types of signatures, can you not foresee a potential problem with your own signatures (or those of your friends) in the near future? Perhaps it had not occurred to you that some other EN World user might decide to object to anything you would put in your signature.
I could bring up "censorship is generally bad" issues, but why bother, I already have six points ...