Not really sure about some of these misunderstandings with the Sehwag-2001/02 situation. The article Sean posted (and Corey quoted the "chilling" part of) is wrong for starters.
The Centurion Park Test was declared unofficial because South Africa did not allow Mike Denness to officiate. South Africa did this because India said they would not play if he was allowed to, and while it was over-petty in some ways there's no doubt Denness' rulings against some of the Indian players in the previous game was over-zealous, especially charging Tendulkar with bringing the game into disrepute for effectively cleaning the seam. The Sehwag ban was a separate issue, it was Tendulkar's wrongful accusation that annoyed people. For South Africa, the revenue from the game being played was more important than the game having Test status. The game was always going to be played, the UCBSA could not afford for it to not be, so they had to accede to India's request to refuse to allow Denness. However, ICC said that if Denness was not allowed to Referee, it would not be a Test, so it wasn't. I don't think either party acted wrongly - if India believed Denness was wholly in the wrong, they should have done that, an unofficial Test was a worthy price to pay. Equally, ICC were quite right to refuse to give Test status to a game where their Referee wasn't allowed to officiate.
India did not refuse to accept Sehwag's ban, it was Denness' continued appointment that they wanted changed, and they got this. However, in the unofficial Test, they left Sehwag out. This meant that as far as the BCCI were concerned, he'd served his ban, but as far as ICC were concerned, he hadn't.
The game that the Sehwag ban caused the issues with was India's next game, against England at Mohali - he was included in the squad, ICC said that if he played then (as with Gambhir now) the game would once more not be given Test status. And in the end Dalmiya backed down and Sehwag did not play in that game, thus serving his ban as ICC said he must. It's unlikely he was ever actually actually going to play, the thing was simply Dalmiya taking the chance to cause a kerfuffle.
The comparison between Sehwag in '01/02 and Gambhir now is wrong. Gambhir's ban is being called by India wrongly imposed; Sehwag's ban they simply argued he'd served it, they did not disagree with it being imposed. As I say, it ended with Dalmiya backing down, the Mohali Test against England went ahead as a Test and there was no problem eventually.
The question is, will the BCCI back down this time? England said they'd refuse to play an unofficial Test in 2001/02. Will the Australians do the same? It'll be interesting to see, but hopefully the BCCI will simply back down, realising that this is a fight even they don't need.