Construction has begun at the site of the Cubs' new spring complex in Mesa, according to this AZcentral.com article:
City Engineer Beth Huning expects an explosion of progress as the new year nears, leading to completion as soon as next October or November. Already, Hunt Construction Group has gone vertical with the walls of a large clubhouse that will house the big-league team’s training facilities and offices. And before long, the steel skeleton of the stadium itself should begin to poke from what used to be Riverview Golf Course. “There’s a lot of things going on all over that site right now,” Huning said — and that includes work at Riverview Park, which will be even fancier than originally planned after voter approval in November of a park-bond package.
Included in that article is a slideshow that has photos of the construction, as well as a couple of renderings of the complex -- two of which you've seen posted here at BCB before, a couple of others I had not seen.
The article also gives some details about the renovation of HoHoKam Park for the Oakland Athletics. The A's and the city of Mesa have not yet signed a deal, but they are expected to in the near future. The A's plan to reduce the seating capacity at HoHoKam -- they don't need the 13,000 seats there for the Cubs. One proposal had the right-field bleacher section (the aluminum benches down the line past the permanent seating) demolished and replaced with an area that would have food stands, making the capacity there about 10,000.
The Cubs still appear to be on track, according to a timeline in the article, to play their first game at the new complex in spring 2014; the A's would move into HoHoKam in 2015. The last Cubs spring game at HoHoKam is scheduled for Thursday, March 28, against the Mariners.