Nothing specific, I am just super excited.
Maybe one specific thing: there's naturally going to be a bit of lag between 'beta is cut!' and 'crates are updated.' So we probably won't have "magical no more breakage constantly land" for a few days after the actual release. I'm gonna try helping out, so if you want a hand, or want to know how to fix some breakage, ping me!
I'd be cautious about claiming that beta won't have breaking changes, I seem to remember we had said something similar for alpha : )
I don't remember such a thing being said for alpha... but it's important to be exact when communicating stability, its true. The announcement post will have real, actual, non-me-being-excited wording. 
Never mind, I think I just extrapolated a bit too much from Announcing Rust 1.0 Alpha | Rust Blog and ignored the "major" part of:
- All 1.0 language features are now in place and we do not expect major breaking changes to them.
- Here again [The core libraries] we do not expect major breaking changes before 1.0.