A post on NeoGAF has an unverified, but legitimate-looking invitation to participate in a trial alpha test for Battlefield 4. This says the version being testing is quite incomplete, being an alpha and all, describing how there will be missing textures, choppy performance, server lag, and downtime. This also says a strict NDA is in place, so we shouldn't expect to hear impressions of the alpha from those who are selected (thanks Strategy Informer). There's a fuller image of the invite from MP1st (thanks VG247 via PC Gamer) with recommended system specs, indicating this will support neither Windows 8 nor 32-bit Windows:

OS: Vista SP2, Win7
Windows 8 not supported
64-bit! 32-bit not supported
DX10 or DX11 GPU with 1+ GB of RAM,
DX11 Highly recommended
25GB Free HDD space required
Latest Origin version required.