Whether it’s “valid” or not humans (and probably most animals) make associations of new, unknown things with similar-seeming known things. In fact, this is the basis of communication.
In the case of discussing new websites/services/devices like Wolfram|Alpha, Bing, Kindle, iPhone, Twitter and so on it’s perfectly reasonable to associate them to their forebears. Until users/society gets comfortable with the new thing and have a way of usefully talking about it making comparisons to known things is effective in forming shared knowledge.
My favorite example of this is Wikipedia and Wikis. What the heck is a wiki? and what the heck is wikipedia based on this wiki? Don’t get me wrong – I know what a wiki is. But to someone who doesn’t, hasn’t used one, and hasn’t contributed to one it’s pretty hard to describe without giving them anchors based on stuff they do know. “Online Encyclopedia”, “Like a Blog but more open”… (for fun read how media used to talk about wikipedia, more here)
More recently is Twitter. What is it like? A chat room? a social network? a simpler blog? IM? right… it’s all that and yet something different, it’s Twitter. You know it when you use it.
Just like in nature new forms are always evolving with technology. Often new tech greatly resembles its ancestories. Other times it doesn’t.
In the specific case of Wolfram|Alpha and Bing/google… they share a common interface in the form of the browser and an HTML text field. They share a similar foundation in trying to make information easy to access. The twist is that Wolfram|Alpha computes over retrieved information and can actually synthesize (combine, plot, correlate) it into new information. Search engines retreive information and synthesize ways to navigate it. Very different end uses, often very complimentary. Wikipedia uses humans to synthesize information into new information, so it shares some concepts with Wolfram|Alpha. Answers.com and other answer sites typically are a mash up of databases and share the concept of web search engines of synthesizing ways to navigate data.
All of these are USEFUL tools and they ARE INTERCONNECTED. None of them will replace each other. Likely they will all co-evolve. And we will evolve our ways of talking about them.