Have a look at https://wiki.ubuntu.com/LucidLynxSchedule
In first place we have Toolchain Conservatively Uploaded as oposed to the Toolchain Uploaded from Karmic.
In Karmic we had 6 alphas, there'll be 1 Beta, then RC and then Final.
In Lucid we have 3 alphas , 2 betas, RC and Final, meaning that the progress made for each "new" alpha is the double as in the old ones, and so they'll be more stable right from the beginning (or should be...)
And finally, they'll be syncing with Debian testing instead of Debian unstable.