No... there is no REBUG 4.85 CFW as of yet. The only current really stable 4.85 CFW is Spy Cobra CFW. Annonymous CFW by Louay has broken Cobra PS2 ISO functions and Overflow CFW is showing the same errors that it did in the 4.83 versions like things disappeaing from the XMB, but is ok other wise. I stick to REBUG 4.84.2 and my own 4.85 CFW that I make, as there is a load of crap 4.85 CFWs out there at the minute.
Jonnie has yet to make a REBUG Lite 4.85 CFW which could be made now, but REX and D-REX reqiure the DEX OFW to make. There may or may not be a new REBUG CFW's coming out, this is up to Joonie as to wether he makes them or not.
deank has now released MutliMAN 4.85.00 BASE adding CFW support from 4.83 to 4.85 ( Though nothing was really needed other than a few alterations for HEN users. So this "Unoffical" version is now null and void and not needed.