What are the current crop of Marzocchi forks like? particulary the 55 and corsa ranges.
Are they still as bombproof and esay to maintain as they used to be?
How do they rack up compared to the rivals, RS/Fox/Magura?

If by 'current crop' you mean 2010 models, I don't know but there are some 2009 ones and even 2008 still on the market and I'd avoid them. My (2008) 55s are currently back with Windwave for the third time. I think they put 2009 'gubbins' in them last time they broke but the 2010 internals are very different – coil sprung instead of air.

The most annoying thing is that I really like them when the feckers work

Sorry should have put 09 or 10 models I've not run them Marz forks since 2006.

avoid forks with the tst2 damper, (at least the 2009 model was) unreliable, and poor performing by design unless you modify the fork internals (it's a simple port orifice damper – spikes badly on high speed hits)

From what Ive seen and ridden the 2010 forks are mint.
Im looking at the Corsa for the XC hardtail.
Personally Id avoid 2008/9 models

interesting as i was considering some used 08 55 tst2 140mm with 09 internals. Not sounding good 🙁

my 2003 z1freerides have never been serviced and i may replace them with the 2010 marz equivalent. the new range looks like marz are back 🙂

interesting as i was considering some used 08 55 tst2 140mm with 09 internals. Not sounding good

unless you don't mind modding fork internals, i'd avoid those. Here's the thread on MTBR about the mod anyhow:
clicky clicky $5