A channel 9 moment

I was flying home this evening on UAL994, IAD-BOS, B752. It was misty in Boston, with RVR fluctuating betwen 1500 and 5000; traffic was landing on 4L and departing on 9. We’d left PVD on the 070 radial to pick up the BOS 4L localizer, and at MILT we’d gone to BOS TWR and been cleared to land. Less than 2 miles out, at about 500 feet, I heard the following exchange on channel 9:
BOS TWR: Eagle Flight 538, cancel takeoff.
Perplexed voice: Er… Eagle Flight 538 is in the air!
BOS TWR: OK, I must have confused you with… Eagle Flight 538, contact departure.
[With apologies to those who don’t grok aviation jargon.]