The Intel Core i7 4790K is a quad-core processor with Hyper Threading (eight threads), comes fully-unlocked for maximum overclocking potential, sports Intel HD Graphics 4600, is still an LGA-1150 socket package, has 8MB of cache, and is clocked at 4GHz for all CPU cores with a 4.4GHz Turbo Frequency.
This 4GHz processor has a new thermal interface (Next Generation Polymer Thermal Interface Material) and that paired with other advancements should make Devil's Canyon great for overclocking.
Intel is also shipping this month their Anniversary Edition Pentium processor in celebration of the Pentium brand turning 20 years old. The Pentium G3258 will be a 3.2GHz dual-core part with an unlocked multiplier and come in well under $100.
Intel is supposed to be sending over some samples shortly so as soon as we get our hands on these refreshed Haswell processors we will be putting them through their paces under Linux (and potentially BSD) at Phoronix. Stay tuned for a lot of interesting Intel Linux benchmarks at Phoronix to whet your appetite while awaiting Broadwell that's still months down the pipe.
In terms of Linux compatibility, given these are Haswell Refresh parts, they should in theory work just fine. We've begun testing Intel 9-Series chipset motherboards and so far the ones we have encountered have worked fine; you can read one of them on the Gigabyte Z97-HD3 while the others are still in my publishing queue.