There's \p{Zs} that matches a normal space and an nbsp and a few other oddities: 
$ perl -le'use charnames (); use warnings; no warnings "utf8"; chr($_)
+=~/[\p{Zs}]/ && printf "%.4x: %s\n", $_, charnames::viacode($_) for 0
+..65500'
0020: SPACE
00a0: NO-BREAK SPACE
1680: OGHAM SPACE MARK
180e: MONGOLIAN VOWEL SEPARATOR
2000: EN QUAD
2001: EM QUAD
2002: EN SPACE
2003: EM SPACE
2004: THREE-PER-EM SPACE
2005: FOUR-PER-EM SPACE
2006: SIX-PER-EM SPACE
2007: FIGURE SPACE
2008: PUNCTUATION SPACE
2009: THIN SPACE
200a: HAIR SPACE
202f: NARROW NO-BREAK SPACE
205f: MEDIUM MATHEMATICAL SPACE
3000: IDEOGRAPHIC SPACE

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(\s also matches it, but only if perl has the string marked as utf8). But \p{Zs} expects an actual NO-BREAK SPACE character, not the HTML entity for one. If you want to include entities that represent space characters, you'd probably be best off using HTML::Entities to decode them first.
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In reply to Re: nbsp in space character class by ysth
in thread nbsp in space character class by hsfrey

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