Hi,
u1 had a lot of "teething pains", but as of u3 MAME is now overall easier to build on Linux than SDLMAME was. You simply type "make" and it autodetects that you're on Linux as well as your CPU type (x86, x64, or PowerPC) and builds appropriately from there. Protip: on most distros you can avoid doing the line-endings dance by simply patching with the --binary parameter (tested and works on Fedora 12 and a recent Ubuntu).
Scale2x was only accessible with you ran with SDLMAME_UNSUPPORTED=1 (meaning you forfeit all support), and as I said in the blog post it never worked completely right anyway.
As always, you'll get faster SDLMAME support at the official forums:
http://www.bannister.org/forums/ but I do try to keep an eye out here
-RB