It seems that they are begining to start to block some web sites from most DNS servers. I recently tried to access MEGAUPLOAD with no success from my standard DNS server.
If anyone else has problems, a quick solution is to use another DNS server, Google's DNS still work. point your network settings to 188.8.131.52 as primary and 184.108.40.206 as secondary and for the time, this should help you access some web sites that are blocked.
As soon as I used this configuration, MEGAUPLOAD was available again.
PS3 CECHA01 REX 4.30.2 CFW 500GB Internal + 9TB/3xHDD; PSP-1001 6.60CFW; PS2 SCPH-3001 160GB FMCB / 3x XBOX XBMC 1x320GB; XBOX360 iXtreme 1.4; Wii 4.3E HBC... ALL thanks to community forums like PS3Hax!!