I did like the talk of changes to the RP & Zealot. This means they still have time to spend on class mechanics so everyone's gripes about their own class (and mine about the SM ;)) could well be on the agenda one day.
Back to the RvR though, I think Carrie is being deliberately protective of anything they've got going on with RvR, and I think any changes might still be so much in their infancy that they wouldn't dare mention anything about them right now.
In fact, I think they're totally in the concept stage for RvR changes. If you read the Massively interview Carrie repeatedly says that all ideas are on the table and that no idea is being ruled out.
"There's nothing off the table"
"Anything's on the table"
Carrie Gouskos, May 12th
If they haven't yet decided which RvR changes they want to make then it's no suprise that there's no mention of this in the letter.
I am confident that RvR changes are incoming and there may well be some hints in the June or July Producer's Letter if they can get some of their ideas/concepts fleshed out a bit and feel confident enough about meeting a release date.
"we do have some really awesome stuff coming -- and 1.4 is a patch that I'm very excited about."Carrie Gouskos, May 12th