Well, as you mentioned, 346 turned 135 earlier this month- on Saturday the 9th to be more exact. She was running for the day of the event, and was given a short reception at the end of the day- celebrating 135 years on god's good earth. Her bear trap spark arrestor was removed, (as you probably noticed in her pictures of double heading with #491), and she was given a brand new cast smokestack to boot! Though it may be a little late, Happy birthday old girl!
As for steam at the CRRM, I can confirm what Mark said- As of now, no events are scheduled for the month of August that will warrant the operation of either 346 or 491. This coming week, the museum will be running both 346 and 491 at different times, so if you're eager to see either engine this summer, now would be the time to do it. After this, 491 will most likely run next for Day out with Thomas in September, and 346 will likely run for Halloween...