Single game tickets will be available in the beginning of March. Don't quote this, but today, I spoke to some people at the Reds that I used to work with and I was told that they will go on sale March 10th or 11th.
As for Opening Day single tickets, there will be no waiting in line this year or camping out for them. They are only available online...once again, don't quote me, but this info came from inside the Reds.
Also, it was blogged by John Fay:
Opening Day tickets
No, I don't have any to give away. But the Reds are close to announcing details of the procedure for this year.
The big change: No Opening Day tickets will be available at Great American Ball Park when single-game tickets go on sale. The club will begin selling Power Packs, probably 11-game Power Packs, March 3. Those packages include Opening Day tickets. If all those sell, no Opening Day tickets will be available. If all the Power Packs don't sell, the remaining Opening Day tickets will be sold in an online sweepstakes.
EDIT: I know that Fay mentions March 3rd, which is very well could end up being on that date...but...like I said, my info came from the Reds, but don't hold me to it being on that date. It will be posted on Reds.com shortly.