Parting is such sweet sorrow. As was announced, Barnes & Noble (NYSE:BKS) has decided the time has come for its progeny -- in this case video game retailer GameStop (NYSE:GME) -- to leave the comforts of home behind and embark on a journey of its own. The bookseller first adopted the company five years ago when it was just a toddler named Babbages and watched with pride as it grew into a strapping teenager with over 1,700 stores and $1.6 billion in annual revenues.

The planned spinoff was completed Friday, and today the two companies are entirely separate entities for the first time. GameStop should have little trouble getting by without a weekly allowance, as this morning it reported a 29% jump in net income (excluding a one-time charge) to $13.8 million, or $0.24 per share, for the third quarter. Sales jumped 28% to $416.7 million, driven by 72 new stores and a double-digit gain in comps.

Management noted that sales are tracking above expectations for nearly every new game that hit the market during the quarter, citing examples such as Grand Theft Auto: San Andreas, the latest version in Take-Two Interactive's (NASDAQ:TTWO) popular franchise, and Microsoft's (NASDAQ:MSFT) Halo 2, which sold more than a half-million copies within the first 24 hours.

That momentum in the market has prompted GameStop to lift full-year guidance, which is now forecast to rise more than 20% to $1.28 to $1.31. That good news is probably enough to inflict Barnes & Noble with a case of "empty nest syndrome," and reports of weak book sales are not likely to help.

Third-quarter revenues at the namesake Barnes & Noble stores edged up 4% to $895 million. Same-store sales showed a slim 0.9% improvement, while comps at the mall-based B. Dalton chain declined 3.3%. The once-separately traded Barnesandnoble.com unit has made few inroads into Motley Fool Stock Advisor pick Amazon.com's (NASDAQ:AMZN) online business, and reported that sales slipped 8% to $91.8 million.

Before the spinoff, Barnes and Noble retained a sizable 59% stake in GameStop in the third quarter, which contributed $7.2 million, or $0.10, to the bottom line -- just enough to offset the $0.09 loss from Barnesandnoble.com. The net result was a disappointing 25% drop in net income to $7.6 million, or $0.10 per share, two cents below estimates. The money-losing online operation wasn't consolidated until last September, though, and on a pro-forma basis, net income actually rose 17%.

Barnes & Noble's third-quarter weakness was somewhat expected, as last year's popular bestsellers -- particularly political and Iraq war-related titles -- made for difficult comparisons. However, earnings of $28 million ($0.38) through the first three quarters are roughly quadruple the $7.4 million ($0.10) earned at this point last year. Furthermore, today's results will likely look good relative to rival Borders Group (NYSE:BGP) , which last month warned of possible third-quarter losses and expectations for declining comps. The nation's leading bookseller will still prosper without the fast-growing, high-margin GameStop subsidiary, but letting go is never easy.

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Fool contributor Nathan Slaughter owns none of the companies mentioned.