FIleSonic has gone offline but it was obvious this was going to happen. The international case against Megaupload has caused other popular file-sharing sites, like FileSonic to add restrictions or completely get out of the business. 

FileSonic did revise their uploading guidelines and claimed that they have been deleting any files associated with copyright infringement. FileSonic lost a low of users with their new policies but stayed online regardless until recently. BBC reported that porn company Flava Works may be taking legal action against FileSonic, accusing the site for assisting their members to distribute copyrighted materials. No word has been received yet from FileSonic so not much details on when or if they will come back online. 

[CNET via BBC]