"So Tim, here's my first question - What actually is poetry?"

Well, Poetry is as various as Music - both in style (Bach, Bebop, Bacharach, Bantu) and purpose (lullabies, soundtracks, hymns, songalongs, propaganda, etc). If two people say they like music, one might be into Garage and the other Plainsong. Two poetry enthusiasts might also have little in common.

In music, fusions are quite possible (Jazz-rock etc). I think that in poetry it's harder to see the joins when styles and purposes are mixed, and switches are more common - The Waste Land's polyphony (with some fragments a word or line long) is hard to do in music.

Music fans make no apology for specialising - if they like brass bands they choose their music friends accordingly - but sometimes I feel that poets who don't understand/like each other's work feel they should stick together anyway to show solidarity against the unbelieving masses. I think some fragmentation of the poetry world is inevitable. I know of poets who say that Larkin's not a poet. I've heard others say that Prynne isn't. And there's the stage/page split - not everybody thinks that Hollie McNish's pieces work off the page. There's Flarf, Doggerel and Found Poetry.

And then there's the march of time - I think some UK pieces that were considered poetry in the 1990s are Flash now. I'm reclassifying some of mine that I wrote back then. And there's the international perspective - there's a tendency in certain periods/countries to view "bad" (or rude, or unpatriotic) poetry as non-poetry.

E-mail and social media has increased the amount and speed of interaction between poets. In the old days a fashion might dominate a nation for years. Nowadays the turnover is so fast that no single style has time to take root - less fashionable styles are frequently re-integrated. This could lead to homogenisation. Fortunately, the improved communication also gives people a chance to find like-minded people, so sustainable niches are more common now, ensuring variety.

Looking back, it's tempting to label poetry eras - "The Movement", etc - but of course many styles of poetry were present in those eras. Nowadays these unfashionable styles remain more visible than before.

So my answer to the original question is the standard one - it depends who you ask, when, and why. Some texts have been considered poetry by many people for a long time. Among those people are academics who influence (at least nationally) what we categorize as poetry. More than ever though, we need to carefully think about what definitions are for.