Semiconductor technology has advanced to the point that the digital representation of a modulated RF signal can be applied directly to a DAC for transmission. Is there, then, any distinction between a "baseband" signal and the RF transmitted signal?
Yes there is an important distinction which is independent of the semiconductor technology. In radio terminology, "baseband signals" are typically centered on "DC" and as such are required to be complex (such as I and Q) to represent a waveform that does not have a symmetrical spectrum about the carrier (basically nearly every modern waveform where modulation of amplitude and phase is involved) while IF signals and "RF Transmitted" signals can be real to represent these same waveforms.
In general "baseband" is the modulated waveform with DC (f=0) as the carrier while "IF signal" and "RF Transmitted signal" are representations with a non-DC carrier.
Terms are going to differ. I think the best I can come up with is that if the signal occupies a relatively narrow slice of the spectrum then it's "RF". If it fully occupies the spectrum -- particularly if it has a DC component -- then it's baseband.
So a recording of me talking, from 300Hz to 3kHz, is baseband (that little slice missing around DC doesn't matter much). A 2.5kHz-wide, SSB-modulated version of me talking, centered around 7.25MHz, is RF, even if it's going out a DAC.
Do you mean either that 1. the sampling bandwidth is large enough to cover the carrier frequency, or 2. demodulation occurs via aliasing when sampling at baseband a modulated signal? I think typically a signal is downconverted to baseband (or upconverted even to a certain frequency) by an analog mixer before sampling. If a signal is sampled at IF, you'll still need to demodulate it digitally. Otherwise it looks as a matter of fact as baseband signal