Around here, 4e is still selling very well and brining in a lot of new players. Personally, in the three groups I'm in, we have 5 new players to 4e D&D. Two of them had never gamed before, two had tried 3.x a few years ago and hated it but love 4e now (the SOs of two of my players), and one of them came back to gaming after taking a break during the 3e years.
Also, one of the players in one of my 4e groups works at the FLGS here. When 4e came out, he wondered if 4e was bringing in new gamers as well, and has kept an unofficial tally whenever he rings up someone buying 4e books. So far from his data, it looks like about 30% of the 4e sales are to new players- mostly young males between 15-22 (many who say they saw a banner ad on a non-tabletop RPG website like for Warcraft, Warhammer Online, etc), adult males over 35 who usually say they are coming back to gaming after a hiatus, and roughly 12% of the people buying 4e are women! The FLGS orders about 20 new PHBs per month, and usually sells them all, and the other core books move 6-10 copies per month. Other big sellers so far have been Martial Power (10 or so per month), Adventurer's Vault (7 per month), and Open Grave (no per month figures yet, but they have sold 20+ of them). In addition, the Dungeon Tile sets sell like mad. In contrast, 3.x and Pathfinder sales are dead around here- they order 4 copies of each new Pathfinder product (2 of the 4 are special standing orders) and manage to sell all 4 copies in about two months. Consider I'm in a town of roughly 180,000 people, and there is a B&N, Borders, and two other game stores (but with no "F" in their name), and I hear from another buddy who works at B&N that their kiosk of D&D 4e stuff moves pretty quickly (requiring restocking most books every other month). Its all anecdotal (which is all any of us have of course), but so far it looks great for the future of 4e around here!