John Sutherland didn't like the sound of it (Plain Jane, please, Comment is free, Guardian, August 21 2008). But I found the first episode of ITV's Lost in Austen very enjoyable: based on the premise of a Jane Austen fan finding herself occupying a missing Elizabeth Bennet's place in Pride and Prejudice, it was well-produced, kept in character throughout, and worked at a variety of levels, from a moment-to-moment "fondant fancy of a drama" (the Radio Times reviewer called it) to a more subtly allusive take on the book for those who know the plot (see the annotated text at the Jane Austen site Republic of Pemberley).
Professor Sutherland likened the concept of Lost in Austen to a formulaic cross-fertilisation of Austen's DNA with that of Life on Mars; I'm mildly surprised he didn't make the connection with many other works using the same motif. Probably the best-known in mainstream literary circles is Woody Allen's The Kugelmass Episode, the story of an unhappily-married professor who meets a magician who can project him into the text of Flaubert's Madame Bovary, with horrible consequences when he finds himself in a very different book.
As described in the commentary at the unofficial Polish site, WoodyAllen.art.pl, the concept can be a vehicle for analysing the text. For instance, Ann-Marie MacDonald's play Goodnight Desdemona (Good Morning Juliet) drops an academic, Constance Ledbelly, into the world of Othello for "comedy, and a feminist reappraisal" (Alex Wheaton, review, dBmagazine). Stella Gibbons' Cold Comfort Farm uses essentially the same idea for satire by putting a highly rational modern young woman into the archaic and irrational world of "loam and lovechild" rural novels. However, the juxtaposition may equally make for less deep but interesting literary play for its own sake: the works of Jasper Fforde use it extensively, his whole series of Thursday Next books being based on the premise of entering alternative book-universes (the first, The Eyre Affair, takes place partially inside an alternative Jane Eyre in which Jane goes to India with St. John Rivers rather than marrying Rochester). Fforde, however, is far from the first: Robert Heinlein's 1980 The Number of the Beast took its heroes into Baum's Oz and a variant on Barsoom (the Mars of Edgar Rice Burroughs); and I first ran into accessible takes on the Elder Edda and Spenser's The Faerie Queene through de Camp & Pratt's Harold Shea series starting with The Incompleat Enchanter.
An interesting variant, where an external person is covertly written into a fictional context, is notorious on the fan fiction circuit as the "Mary-Sue", where that external person is the writer. Mary-Sue is, for instance, the impossible talented young ensign who saves the starship Enterprise and becomes the love of Captain Kirk (the male equivalent is the "Marty-Stu"). Too good to be true: 150 Years of Mary Sue by Pat Pflieger analyses the phenomenon, noting that it had its equivalents in the pages of the 19th century periodical Robert Merry's Museum. At The Other World blog, Clio: Mary-Sue in history argues further that it applies to some fictionalised historical biographies; one identified author admits, surprisingly, that to some extent it may be a fair cop.
Addendum: see The Yiddish Policeman's Universe, a post at Felix Grant's Growlery, where we're swapping examples of books and other works that, in various senses, explore alternate realities.
Addendum #2: Another view (Professor Kathryn Sutherland, The Guardian, Tuesday September 9 2008) : the author of Jane Austen's Textual Lives (OUP, 2005, ISBN 0199258724) takes a further glance at Lost in Austen. The piece doesn't say much, but does note what I thought was part of its interest: that it's not just playing with the novel, but also alluding to previous film and TV adaptations. I didn't realise that there's also a book by Emma Campbell Webster - Lost in Austen (UK title Being Elizabeth Bennet) which presents commentary on Jane Austen's novels in role-play format - some choices leading to lethal outcomes - in what looks like a highly creative way to explore familiar texts.
Follow-up: there's more comment and discussion in a later post, Lost in admiration.