30 Rock

I haven't actually watched this show, but it's having a season premier this week. As I understand it, Alec Baldwin does a good job playing Jack, a crazy network executive in the show. There's a review in the New York Times Sophomore Jitters and Seinfeld Vision :

Jack has decided to increase advertising revenues by digitally inserting Mr. Seinfeld into NBC shows like “Law & Order” and “Deal or No Deal.” Jack calls his computer-generated fakery “SeinfeldVision.” The counterfeited comedian shows up at Rockefeller Center to complain, and that’s when the show goes a little wobbly: Mr. Seinfeld is strangely ill at ease playing himself, making his self-impersonation unpersuasive.

Tina Fey is the creator of the show and also appears in it. In real life she has a family and a very busy schedule - here's a quote from a recent interview:

"At home,” she added, “I cry” — about, among other things, not being home enough.