The ESRB website has recently been updated to include two new entries for GTA games on the PlayStation 3, one for Grand Theft Auto 3, the other for Vice City. The publisher in both cases is listed as Sony Computer Entertainment America, which suggests both titles will be appearing as PS2 classics. This unfortunately means they're unlikely to be on the receiving end of any HD treatment, but still, they'll be nice to have in your collection.
There's no official word from Rockstar on this, so we don't know of any release dates or pricing information. We're also not sure why San Andreas has curiously been left out, and/or if it may appear at a later date.
On a slightly related note, this year will be Vice City's 10th anniversary. If Rockstar are planning similar things to what they've been doing for GTA3, it wouldn't surprise me at all if we see Vice City appearing on iOS and Android later this year either.
Thanks to R* Network for the heads up.