Its strange that Tap has no mention of the latest news on their website. Although I did find this press release of Tap reinforcing flights to Venezuela as of June 2005.
I think this can only be positive for TAP. It is a great alliance. They did a good thing to join it. Better than the qualifyer group where they were in a long time ago. They got out just in time.
The main reason that Tap opted for Star Alliance instead of Oneworld is simple. Iberia beeing a major player in the Iberian Peninsula, belongs to Oneworld so to mark their territory Tap opted for Star as the most logical decision.