Apple CEO Steve Jobs will open up Macworld Expo, San Francisco with a keynote speech tomorrow at 6pm (UK time) - and speculation as to Apple's plans have already forced one company competitor to take preventative action to protect its business.

US online film service Netflix has confirmed plans to lift its limits as to how long its customers can watch films and television shows over the internet. The move comes as rampant rumour and speculation claiming that Apple will introduce a film and television show rental service through iTunes prevails.

Apple will charge $3.99 for movies that can be downloaded and played for up to 24 hours, multiple reports claim.

Perhaps with this in mind, Netflix will allow subscribers to stream as many films and TV shows as they like from its 6,000 item catalogue, though this material is only viewable on a computer at this time, until solutions that allow such media to be streamed to a television are released later in the year.

Apple already has such a solution in the form of its slow-sellling Apple TV, giving rise to speculation that the company will improve its streaming media solution with a new version of the product that may also be revealed during Jobs' keynote speech.

Speculation as to the content of Jobs' speech is rife. Apple yesterday began unfurling banners around the San Francisco venue for the annual event declaring, simply: "There's something in the air".

Whether this is a reference to the famous Thunderclap Newman song of that name, which carries on to declare, "because the revolution's here," is open to debate, but the phrase tends to indicate the event will witness some moves in the wireless space.

Potential moves here could include a 3G iPhone (though most Apple-watchers don't expect that product to appear until later this year), an improved AppleTV, an over the air music or film purchase/rental service, or even the introduction of some form (client or server install) of WiMax support through future Macs.

Even so, the jury remains out at this stage of the pre-Expo bingo game, with additional reports claiming the company may introduce its much-discussed touch-sensitive sub-notebook MacBook at the show.

Other reports speculate Apple may announce its support of - and introduce solutions designed to support - the next-gen high definition DVD format, Blu-Ray. It has been reported that Apple may have reached a deal with the studios to allow Blu-Ray DVDs to be copied into a person's iTunes library.

Mulling Macworld, Piper Jaffray analyst Gene Munster told the Financial Times: “It is highly unlikely that this year’s Macworld will have the same splash as last year."