Two times since I installed 3.15-rc2, my desktop system has booted to the lightdm login with the keyboard not available for input. This hardware runs 24/7/365 and will soon be 4 years old, and the CPU has been overclocked most of the time, so it is possible that the hardware is getting tired. But I have not observed this issue with any previous kernel, so I thought it might be good to post it. Both times, it booted correctly the second time.
don@imerabox:/$ lsusb | egrep Keyboard
Bus 006 Device 002: ID 045e:00db Microsoft Corp. Natural Ergonomic Keyboard 4000 V1.0
System: Host: imerabox Kernel: 3.15-rc2-siduction-amd64 x86_64 (64 bit gcc: 4.8.2)
Desktop: KDE 4.12.4 (Qt 4.8.6) Distro: aptosid 2011-02 Ἡμέρα - kde-lite - (201107131633)
Machine: Mobo: ASUSTeK model: P6X58D-E v: Rev 1.xx Bios: American Megatrends v: 0803 date: 08/06/2012
CPU: Quad core Intel Core i7 CPU 950 (-HT-MCP-) cache: 8192 KB
flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 22408
Clock Speeds: 1: 2801 MHz 2: 2801 MHz 3: 2801 MHz 4: 2801 MHz 5: 1600 MHz 6: 1600 MHz 7: 1600 MHz
8: 1867 MHz
Graphics: Card: NVIDIA GF100 [GeForce GTX 480] bus-ID: 05:00.0
Display Server: X.Org 1.15.1 driver: nvidia Resolution: 1920x1200@59.9hz
GLX Renderer: GeForce GTX 480/PCIe/SSE2 GLX Version: 4.4.0 NVIDIA 337.12 Direct Rendering: Yes
Network: Card: Marvell 88E8056 PCI-E Gigabit Ethernet Controller
driver: sky2 v: 1.30 port: d800 bus-ID: 06:00.0
IF: eth0 state: up speed: 100 Mbps duplex: full mac: 20:cf:30:5c:41:1d
Drives: HDD Total Size: 2136.5GB (2.2% used) model: OCZ
model: OCZ model: KINGSTON_SS100S2
model: WDC_WD1002FAEX model: WDC_WD1002FAEX
Info: Processes: 328 Uptime: 30 min Memory: 1806.5/5965.7MB Init: systemd runlevel: 5 Gcc sys: 4.8.2
Client: Shell (bash 4.3.111) inxi: 2.1.20