DirecTV is doing the first week of MLB package for free. Ends tomorrow.
In Demand was also doing this. So everyone should check their cable listings for the MLB Extra Innings channels, the games should be on.
There should also be another free preview week at some point this summer, usually when the half-season package goes on sale.
I'm actually glad there was a preview this week. It was enough for me to know that I wasn't going to order it. Standard definition games only, not every game has both home and away feeds, not every game will be shown. (This was on my system anyway, your mileage may vary).
The online package is cheaper, has both feeds for every game, has both radio feeds for every game, has archives for every game. The picture quality is great (if you have a fast enough internet connection). I can watch on my TV through my media center PC, or I can take the laptop out on the patio and enjoy the game outside. (Which I did last night.)
Usually at some point during the season there will be an offer to sign up for a free week of the online package. If I see it when it comes up, I'll post the info here.