Accusing Apple of fostering a monopoly in iPods is, to steal an analogy from Megan McArdle, like accusing P&G of fostering a monopoly in Charmin. There are other media players. There are other smart phones. There are other viable music stores.
I find the comparison between iTunes and Windows says more about the complainant than it does about Apple. Microsoft's monopoly prevented the development of competing technologies and enabled Microsoft to shut down entire sectors of the industry. Having the market's favorite music player doesn't prevent Amazon from selling music or Last.fm from streaming music or Microsoft from distributing Zunes.