There is an open argument happening on the Web, sparking passionate debate (and random flaming) on both sides of the fence regarding Mike Arrington’s recent closure of TechCrunch’s UK blog. It’s getting ugly and there are lessons to be learned from it.

A bit of background if you’re in the dark:

Mike Arrington is the owner of TechCrunch, one of the most prominent and popular tech / Web 2.0 blogs, which has fast grown from one popular site into a media network (Om Malik is doing something similar at GigaOM). One of the members of the network was TechCrunch UK, which was being run by Sam Sethi.

To cut a very long story short, due to a difference of opinions regarding how Sam reported on Le Web 3 (a recent European conference) and how the follow up comments in his blog where handled, Mike terminated the relationship. Or Sam terminated the relationship. Depends which side you’re on.

It’s now come to a head. Mike posted a very – let’s just call it bold – entry on CrunchNotes (the insider blog for TechCrunch network happenings) explaining in frightening detail the ‘facts’ of the situation.

You need only examine the comments and the ensuing conversation on the Web to learn that this professional disagreement is getting somewhat out of control. It’s one of those nasty situations where regardless of who is right or wrong, both parties are (despite some nice Web buzz) jeopardizing their online brands.

Lessons to be learned:

1. Even if it’s Web 2.0 business, it’s still business. Conduct yourself professionally in the web space as you would in ANY professional space.

2. Don’t discuss over email or IM, or even worse and open blog post, what should by all accounts be discussed face to face over a beer. Mike Arrington is wrong. So is Sam Sethi. They have both stepped over the line.

3. The Web is like an elephant. It never forgets. There is one overriding thought behind all the content I ever put on the Web: “One day, when my kid is searching Google (if that’s even what he’ll be doing then, but you catch my drift) – would I want him to see this?”

If you cannot answer that affirmatively without doubt, rather shut your mouth.

Yes, this social Web evolution is exciting. Transparency, authenticity and integrity are wonderful, powerful drivers. But this has just gotten a little too transparent, and authenticity and integrity are suffering for it.

Mike and Sam – neither of you know me and I’ve positive neither of you care less. But the way you’ve both handled yourselves is disappointing.