Trademark 2.0?

O'Reilly Media is a company that produces a host of technical and computer books, courses and conferences. Their output is generally quite good and you'll probably find a few of their books on the bookshelf of most computer professionals.

However they have been getting a fair bit of flack in the online community in the last week for their decision to set their lawyers on a nonprofit group down in Cork that wanted to have "Web 2.0" conference. The problem? O'Reilly claim a trademark on "Web 2.0". O'Reilly sent in the lawyers before contacting the conference organisers and in fairness to them have now apologized and allowed the conference to use the phrase.

This got me curious so I had a look at the O'Reilly web site and it currently lists another upcoming conference using another term, Where 2.0. I presume they also claim the trademark over that, it does have TM on it. Now I wonder, can a company really claim a trademark on an existing widely used word, not even a phrase, simply by adding 2.0 to it? Should I just grab the Oxford English dictionary, write "All the above plus 2.0" on the last page, head down to the trademark registration office and wait for the money to roll in?