There's an interesting blog post on some practical implications of HTTP2 by Mark Nottingham, chair the IETF HTTPbis Working Group (the group that is working on the standard).
He gives a nice rundown on some of the implications of the HTTP2 rollout:
HTTP/2 is getting close to being real, with lots of discussions and more implementations popping up every week. What does a new version of the Web’s protocol mean for you? ... The Web performance community’s mantra is “avoid HTTP requests” because HTTP/1 make them expensive. This has given rise to techniques like inlining, concatenation and spriting to reduce the number of requests on a page. With HTTP/2, these techniques shouldn’t be necessary... -- src: [mnot.net...]
it's a binary protocol, so no more manually crafting headers in text.
major browser builders have said they will only support a TLS connections (encrypted) in HTTP2. This is partly to encourage more websites to use encryption, but it's made reasonable by the fact that encrypted connections will be a lot cheaper in HTTP2
Many of the boxes that make up the web were built on the assumption that HTTP 1 would last forever and therefore are hard to upgrade, which will slow the rollout. This is the other part of the reason for allowing only TLS connections.
It's an interesting glimpse into the probable future of the internet.
I should add, the other reason for forcing the TLS connection is that intermediate machines won't tamper with encrypted data and are forced to send it on exactly as received. That means that if an intermediate machine is HTTP 1 only, it won't completely bork the transmission.
So as a method of phased rollout that's compatible with old servers and switches, this is pretty much a requirement for the foreseeable future.