For example, Motorola tweeted probably the snarkiest response during the iPhone 5 unveiling.
Microsoft also took a pot shot at the then-new phone.
Twitter wouldn't comment on any marketing strategies for the upcoming event, but director of brand strategy Ross Hoffman said in an email: "Past precedent shows there's always significant conversation around Apple launches coming from consumers and brands alike."
This sort of real-time marketing strategy now "happens at all the major events," said Jason Stein, president of social media marketing firm Laundry Service. In certain circumstances it can even be successful for a brand, he said.
But an event like Apple's product unveiling is a "no-win situation for competitors," Stein said. The event is a popular company unveiling popular products, and thus sucks up most of the available media oxygen.
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Efforts to hijack the event via Twitter either to denigrate the brand, or change the conversation inevitably reflect badly on the originator, he said.
"It's a huge mistake to attack [Apple]. It makes you seem desperate and lame," Stein said. Stein described Motorola's "Lazy" tweet as a "fail on every level."
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Still, this strategy has some benefits to those who employ it correctly. Social media analysis firm Mashwork said the only brand to really have a successful play was Nokia, whose strategy was aided by the fact that their tweet was light-hearted, said Shelia Seles, product marketing lead for Mashwork.
The company's tweet, which suggested that iPhones were an imitation of Nokia phones, was re-tweeted 16,000 times in the first 24 hours, according to Mashwork.
It was by far the most retweeted tweet about anything iPhone-related that day. Rivals Motorola (600 retweets), and Windows (slightly more that 1,100 retweets), both of whom took a snarky, critical attitude, were not nearly as successful, Seles said.
The lesson: Taking an unwarranted jab at a competitor does your brand no favors, she said.
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Still, the temptation to insert their products into the online conversation about Apple will probably prove irresistible to many of the major smartphone companies, Seles said. "It just makes a lot of strategic sense."
Knowing how much public speculation has been given to Apple's likely smartwatch, it (assuming one is announced) is likely to be the target of rivals' tweets, especially given the face that the watch is unlikely to be available until next year, Seles said.
Spokespeople for Samsung, Microsoft and Nokia declined to comment, and a spokesperson for Motorola did not return emails.
—By CNBC's Matt Hunter.