If you currently have a Haswell CPU, updates are coming as soon as May if you're not into overclocking. If you want a shiney new i7-4790K, you'll need to wait until June. The 4790 is expected to come in at 3.6GHz stock, compared to 3.4GHz on a 4770, and 3.5GHz on a 4770K/4771. No specs on the 4790K available.
If you don't currently have Haswell, but were thinking about upgrading, save your money. Broadwell comes out in the fall. No specs on that yet either, but Intel has said they expect a 30% reduction in power usage with Broadwell, mainly because it'll be made on a 14nm process, where Haswell and Ivy Bridge are 22nm.
Also expect Haswell-E late summer or early fall. Finally time for DDR4 8-core desktop CPUs :D
Also expect motherboard makers to go completely insane trying to keep up with all of these things happening at once :)
Nvidia's new Maxwell architecture is also coming, probably starting sround March, but they're giving us the entry level chip first, which will basically mean upgrades for the GT 630 and 640. It'll be a few months later for the mid and high-end GPUs.
A ton of stuff happening this year ensuring we get more BOINCing done using less power and producing less heat. This will be a great year.