SocialnetworkfeverspreadstotheprofessionsWhensocialnetworksfirstappearedafewyearsago,itwaswidelybelievedthisphenomenonwouldbelimitedtocrazedteenagersalreadyincapacitatedbyexcessivetimespentonvideogamemachines.MostserioustechnoratisinSiliconValley,andWallStreet,feltthiswasabliponthehorizon,andtheirfullattentionwasoccupiedprimarilybyseachengines,searchenginemarketing,andadplacement.Butwhenthepopulationofsocialnetworkparticipantspushedpast50million,then75million,evenhetechnicalelitewokeuptothefactthatthesehugeaudienceswerenotjustabunchofteenagers,butthatinsteadawidesliceofAmericansocietywasalsoparticipating.steveballmer,CEOofMicrosoft,saidinSeptember2007that“Ithinkthesethings(socialnetworks)aregoingtohavesomelegs,andyetthere’safaddishness,afaddishnatureaboutanythingthatbasicallyappealstoyoungerpeople.”thiswasamonthbeforeMicrosoftpaid$250millionforasmallstakeinfacebook,whichvaluedthecompanyat$15billion.MyspaceinthemeantimehadpassedYahooasthemostfrequentlyvisitedsiteontheweb.tryingtosoundconvincing,ericSchmidt,CEOofgoogle,declaredthat“Iknowalotofpeoplethinkthis(socialnetworking)isablip,butit’sreal.it’sserious.”Hesaidthisjustbeforespending$1.65billionforyoutobe.Thesocialnetworkingcrazeobviouslyhasawakenedthetechnologygiants,buttheyfocusmostlyonthereallyhugeaudiencesattractedtothegeneralnetworkingsitessuchasmyspace,facebook,youtobe,andorkut(google’ssocialnetworkingsitethatistheleaderinbrazialbuthasfloppedintheunitedstates).However,inthebackgroundthereareafast-growingcollectionofsocialnetworksthatareaimedatcommunitiesofpractitionersorspecificinterestgroups.Takelinkedin,forexample,probablythebest-knownbusinessnetworkingsite.LinkedInisanonlinenetworkwithmorethan24millionworldwidemembers,representing150differentindustries.every25daysarso,anothermillionpeoplelinkedin.linkedinallowsamembertocreateaprofile,includingaphoto,thatsummarizeshisorherprofessionalaccomplishments.member’snetworksincludetheirconnections,theirconnections’connections,aswellaspeopletheyknow,potentia