The latter three games are expected within the first half of next year, with the most significant postponement affecting BioShock 2. Originally scheduled for November 2009, Take-Two now claims the game will arrive in the first half of calendar 2010. The difference there could be quite a few months, indicating that isn't just a minor issue they are concerned about.
The reason is unclear at the moment. Take-Two only specified that it would be the right decision in terms of development, but did attempt to clarify that cross-development among numerous platforms didn't play a part in the setback. The bottom line is that Take-Two claims more development time is needed to produce a quality product – which is what a gamer should expect from any developer. I would rather wait six months or even longer for a game to come out of development than get hit with a half-release that is full of bugs.
Take-Two may reveal more details later in day. One definite bad note for Take-Two is that they will miss the influx of buyers at the end of the year, which could potentially harm their bottom line.