This is a BAD THING because Rich was a significant figure on the right-lite side of the National Party - the wing of the party that isn't insane, in thrall to free market ideology. The wing which actually represents a significant constituency in New Zealand, but which has struggled to be heard in the National Party of late. Rich was never a good fit in the National Party under Brash. Key rehabilitated her, to show that there were no hard feelings and he wasn't at all like his predeceessor, but since he hasn't rejected the freemarket extremism of Brash et al, and seems to be biding his time before implementing it, her survival in government was doubtful.
It is also interesting that National will certainly be looking to coalesce with ACT, if they don't have the numbers to go it alone. ACT voted against the repeal of section 59, whereas Rich supported Bradford's bill from the start (2). ACT are making a lot of noise about a referendum on the repeal (3). If National need them, it would be something they would push for - an opportunity to grandstand and claim that their absurd little libertarian party is in tune with mainstream New Zealand, instead of the muddy little creek it actual is. Might Rich have see this, and realised that she - unlike her party leader - didn't want to swallow that particular rat?
1 - 'Rich drops resignation bombshell,' by Colin Espiner in The Press, 13th of February, 2008. Reproduced on stuff.co.nz. (http://www.stuff.co.nz/stuff/4399450a10.html)
2 - 'ACT pushes anti-smacking referendum,' press release by the ACT party, 2nd of February, 2008. (http://www.act.org.nz/act_pushes_anti-smacking_referendum)
3- Espiner, op. cit.