The story is actually from Fortune magazine (which lives on the cnn.com domain). I presume that Arrington didn't post about it on TechCrunch because he may not have been ready to make the announcement yet, if the news is in fact true.

From the linked article: Neither Arrington nor AOL responded to requests for comment. Gallagher said "no comment" when reached via phone.

In April, he wrote: "in a few months, there’s a very good chance that I’ll be a direct or indirect investor in a lot of the new startups in Silicon Valley"

http://techcrunch.com/2011/04/27/an-update-to-my-investment-...

Why is it ironic? It's the finance and money column of a news outlet, and this is financial news.

Yes there is a great deal of irony in standard business practices. No irony intended.