Consoles are getting some new DLC for Resident Evil 5 in February and March. That content, unfortunately, is not planned for PC "at this point."
A Capcom spokesperson told a member of the G4TV staff that there were "No plans for PC at this point." That comes as a bit of a shock since Capcom's recent push to PC gaming with the PC-lead projects news in September.
If you're still curious, be sure to check out information on the DLC with the OKC Console Game Examiner. There are dates, details, and a slideshow if you have a console to play it on!