This year I've simplified things for myself (just not enough time otherwise), so as far as seedlings for sale starting in mid April, it will be mostly tomatoes, with a good (but not as large as previous years) selection of hot and sweet peppers and eggplant. This coming year I will not have lettuce, basil, cukes, melons or tomatillo seedlings available.
I've just completed transplant of my beet, greens and lettuce seedlings from the crowded 50 cell plug flats to individual cells (for beets and greens), or 3 1/2 inch pots, for lettuce. I've just uncovered the back two rows of my garden, pushing aside the leaves, and will turn the rows over in the next few days in preparation to receive the beets, lettuce and greens.
The peppers, eggplant and tomato seedlings are now spending all day and night outdoors in the crowded 50 cell plug flats. True leaves should appear soon, and if the night time temps hold at 35 or warmer, I will begin transplanting into 3 1/2 inch pots in a week or so. After that, it all depends upon daytime and nighttime temps. My current guess on seedling availability is Friday April 12, running for a month or so. You can get a sense of the variety list on the page here (scroll down a way to find the lists)
The Dwarf project marches on, and I hope to squeeze another 100 or so examples into my driveway garden. The project has done really well, and by this fall we should be approaching over 20 new releases, with dozens more in progress.
So that's where things are - I am balancing the seedling work with book writing, which continues to go well, heading toward a June 1 deadline for the text.