Inevitably, questions about whether and/or why the SW is so slow to be adopted arise and I think it's worthwhile to respond. First, let's take a step back for an extremely brief review of the World Wide Web's (WWW) evolution. After being released in 1991, the Web made its first steps into e-commerce around 1995 - four years later. (Note that at the time, any hint of commercialism was blasphemy to the people that had populated the Web to that point.) In the late 1990's the world experienced a colossal explosion of innovation and Web adoption. Millions were being poured into Web ventures (anyone remember webvan.com? They IPO'd November, 1999 and raised $375 million. The company went out of business in mid-2001.)
The buzz and the vast sums certainly attracted attention and adoption, but at its core, the WWW was a combination of relatively simple technologies like HTML, TCP/IP, HTTP, lightweight browsers, and modem technology that had been around for decades. These latter factors were central to making it easy to go online and pursue your interests, whether they might be chatting, reading, shopping, or seemingly aimless "surfing." In any case, it took about ten years to go from launch to boom to bust and seems to have left the impression that success online is defined by getting big and doing it fast.
The SW is considerably more complex than the WWW. As an extension of the WWW, it's considerably more powerful, but it ain't easy stuff to learn. Further, at least for the moment, there aren't any visible applications that are as compelling as what people were exposed to when the WWW began to take off (and I don't consider development tools to be mainstream applications.) So considering its complexity, "invisibility", and the fact that the initial SW constructs were released about a few years after the WWW, I think we're doing pretty well. Note that W3C issued its XML 1.0 recommendation Feb 10, 1998.
In fact, given the number of technologies (read: standards) required to make the SW really perform and how recently some important and fundamental recommendations have been issued (OWL: Jan '04; RDF: Feb '04; SPARQL: Jan '08), I'd actually say the SW is moving along quite nicely.
Getting back to reality, I have to admit to wishing that the SW emulated the adoption curve of something like Facebook and that we were all making millions - daily! But the fact is that the SW may be around for far longer than Facebook and it may reach far greater heights. I've been at this since late 2003 and given the level of interest I'm seeing from a growing number of major players, I think I'm going to stick around for a while longer.