Found crack in cylindrical part inside A/C condenser unit

I had my Central A/C tuned up at the beginning of June.  It has been
working nicely, I still am getting cooling.  My unit is a 4 ton
Carrier system.  It is an older system that uses R22.

Today, I happened to take a peak through the top of the condenser
unit, and noticed that there is a crack in the metal case of light
grey colored cylindrical part.

Here are links to 2 photos:

http://mysite.verizon.net/vzeofpch/cracked_ac.jpg

and

http://mysite.verizon.net/vzeofpch/cracked_ac2.jpg

What part is this?  Does the crack in the metal case mean failure will
soon happen...if so how soon?  What is the brown stuff I see on the
side of this part below the crack...is this oil?  Do I have a freon
leak?

Nobody mentioned this during my tune-up.  From the looks of it, it's
hard to believe the crack didn't exist at the beginning of the month
at all, and they didn't need to add any freon because pressure was
fine, and I'm still getting adequate cooling as far as I can tell.

Does anything need to be done?

Thanks,

Jay